asd

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_fitpack.py

@@ -0,0 +1,503 @@
+import itertools
+import os
+
+import numpy as np
+from numpy.testing import (assert_equal, assert_allclose, assert_,
+                           assert_almost_equal, assert_array_almost_equal)
+from pytest import raises as assert_raises
+import pytest
+from scipy._lib._testutils import check_free_memory
+
+from scipy.interpolate import RectBivariateSpline
+
+from scipy.interpolate._fitpack_py import (splrep, splev, bisplrep, bisplev,
+     sproot, splprep, splint, spalde, splder, splantider, insert, dblint)
+from scipy.interpolate._dfitpack import regrid_smth
+from scipy.interpolate._fitpack2 import dfitpack_int
+
+
+def data_file(basename):
+    return os.path.join(os.path.abspath(os.path.dirname(__file__)),
+                        'data', basename)
+
+
+def norm2(x):
+    return np.sqrt(np.dot(x.T, x))
+
+
+def f1(x, d=0):
+    """Derivatives of sin->cos->-sin->-cos."""
+    if d % 4 == 0:
+        return np.sin(x)
+    if d % 4 == 1:
+        return np.cos(x)
+    if d % 4 == 2:
+        return -np.sin(x)
+    if d % 4 == 3:
+        return -np.cos(x)
+
+
+def makepairs(x, y):
+    """Helper function to create an array of pairs of x and y."""
+    xy = np.array(list(itertools.product(np.asarray(x), np.asarray(y))))
+    return xy.T
+
+
+class TestSmokeTests:
+    """
+    Smoke tests (with a few asserts) for fitpack routines -- mostly
+    check that they are runnable
+    """
+    def check_1(self, per=0, s=0, a=0, b=2*np.pi, at_nodes=False,
+                xb=None, xe=None):
+        if xb is None:
+            xb = a
+        if xe is None:
+            xe = b
+
+        N = 20
+        # nodes and middle points of the nodes
+        x = np.linspace(a, b, N + 1)
+        x1 = a + (b - a) * np.arange(1, N, dtype=float) / float(N - 1)
+        v = f1(x)
+
+        def err_est(k, d):
+            # Assume f has all derivatives < 1
+            h = 1.0 / N
+            tol = 5 * h**(.75*(k-d))
+            if s > 0:
+                tol += 1e5*s
+            return tol
+
+        for k in range(1, 6):
+            tck = splrep(x, v, s=s, per=per, k=k, xe=xe)
+            tt = tck[0][k:-k] if at_nodes else x1
+
+            for d in range(k+1):
+                tol = err_est(k, d)
+                err = norm2(f1(tt, d) - splev(tt, tck, d)) / norm2(f1(tt, d))
+                assert err < tol
+
+    def check_2(self, per=0, N=20, ia=0, ib=2*np.pi):
+        a, b, dx = 0, 2*np.pi, 0.2*np.pi
+        x = np.linspace(a, b, N+1)    # nodes
+        v = np.sin(x)
+
+        def err_est(k, d):
+            # Assume f has all derivatives < 1
+            h = 1.0 / N
+            tol = 5 * h**(.75*(k-d))
+            return tol
+
+        nk = []
+        for k in range(1, 6):
+            tck = splrep(x, v, s=0, per=per, k=k, xe=b)
+            nk.append([splint(ia, ib, tck), spalde(dx, tck)])
+
+        k = 1
+        for r in nk:
+            d = 0
+            for dr in r[1]:
+                tol = err_est(k, d)
+                assert_allclose(dr, f1(dx, d), atol=0, rtol=tol)
+                d = d+1
+            k = k+1
+
+    def test_smoke_splrep_splev(self):
+        self.check_1(s=1e-6)
+        self.check_1(b=1.5*np.pi)
+        self.check_1(b=1.5*np.pi, xe=2*np.pi, per=1, s=1e-1)
+
+    @pytest.mark.parametrize('per', [0, 1])
+    @pytest.mark.parametrize('at_nodes', [True, False])
+    def test_smoke_splrep_splev_2(self, per, at_nodes):
+        self.check_1(per=per, at_nodes=at_nodes)
+
+    @pytest.mark.parametrize('N', [20, 50])
+    @pytest.mark.parametrize('per', [0, 1])
+    def test_smoke_splint_spalde(self, N, per):
+        self.check_2(per=per, N=N)
+
+    @pytest.mark.parametrize('N', [20, 50])
+    @pytest.mark.parametrize('per', [0, 1])
+    def test_smoke_splint_spalde_iaib(self, N, per):
+        self.check_2(ia=0.2*np.pi, ib=np.pi, N=N, per=per)
+
+    def test_smoke_sproot(self):
+        # sproot is only implemented for k=3
+        a, b = 0.1, 15
+        x = np.linspace(a, b, 20)
+        v = np.sin(x)
+
+        for k in [1, 2, 4, 5]:
+            tck = splrep(x, v, s=0, per=0, k=k, xe=b)
+            with assert_raises(ValueError):
+                sproot(tck)
+
+        k = 3
+        tck = splrep(x, v, s=0, k=3)
+        roots = sproot(tck)
+        assert_allclose(splev(roots, tck), 0, atol=1e-10, rtol=1e-10)
+        assert_allclose(roots, np.pi * np.array([1, 2, 3, 4]), rtol=1e-3)
+
+    @pytest.mark.parametrize('N', [20, 50])
+    @pytest.mark.parametrize('k', [1, 2, 3, 4, 5])
+    def test_smoke_splprep_splrep_splev(self, N, k):
+        a, b, dx = 0, 2.*np.pi, 0.2*np.pi
+        x = np.linspace(a, b, N+1)    # nodes
+        v = np.sin(x)
+
+        tckp, u = splprep([x, v], s=0, per=0, k=k, nest=-1)
+        uv = splev(dx, tckp)
+        err1 = abs(uv[1] - np.sin(uv[0]))
+        assert err1 < 1e-2
+
+        tck = splrep(x, v, s=0, per=0, k=k)
+        err2 = abs(splev(uv[0], tck) - np.sin(uv[0]))
+        assert err2 < 1e-2
+
+        # Derivatives of parametric cubic spline at u (first function)
+        if k == 3:
+            tckp, u = splprep([x, v], s=0, per=0, k=k, nest=-1)
+            for d in range(1, k+1):
+                uv = splev(dx, tckp, d)
+
+    def test_smoke_bisplrep_bisplev(self):
+        xb, xe = 0, 2.*np.pi
+        yb, ye = 0, 2.*np.pi
+        kx, ky = 3, 3
+        Nx, Ny = 20, 20
+
+        def f2(x, y):
+            return np.sin(x+y)
+
+        x = np.linspace(xb, xe, Nx + 1)
+        y = np.linspace(yb, ye, Ny + 1)
+        xy = makepairs(x, y)
+        tck = bisplrep(xy[0], xy[1], f2(xy[0], xy[1]), s=0, kx=kx, ky=ky)
+
+        tt = [tck[0][kx:-kx], tck[1][ky:-ky]]
+        t2 = makepairs(tt[0], tt[1])
+        v1 = bisplev(tt[0], tt[1], tck)
+        v2 = f2(t2[0], t2[1])
+        v2.shape = len(tt[0]), len(tt[1])
+
+        assert norm2(np.ravel(v1 - v2)) < 1e-2
+
+
+class TestSplev:
+    def test_1d_shape(self):
+        x = [1,2,3,4,5]
+        y = [4,5,6,7,8]
+        tck = splrep(x, y)
+        z = splev([1], tck)
+        assert_equal(z.shape, (1,))
+        z = splev(1, tck)
+        assert_equal(z.shape, ())
+
+    def test_2d_shape(self):
+        x = [1, 2, 3, 4, 5]
+        y = [4, 5, 6, 7, 8]
+        tck = splrep(x, y)
+        t = np.array([[1.0, 1.5, 2.0, 2.5],
+                      [3.0, 3.5, 4.0, 4.5]])
+        z = splev(t, tck)
+        z0 = splev(t[0], tck)
+        z1 = splev(t[1], tck)
+        assert_equal(z, np.vstack((z0, z1)))
+
+    def test_extrapolation_modes(self):
+        # test extrapolation modes
+        #    * if ext=0, return the extrapolated value.
+        #    * if ext=1, return 0
+        #    * if ext=2, raise a ValueError
+        #    * if ext=3, return the boundary value.
+        x = [1,2,3]
+        y = [0,2,4]
+        tck = splrep(x, y, k=1)
+
+        rstl = [[-2, 6], [0, 0], None, [0, 4]]
+        for ext in (0, 1, 3):
+            assert_array_almost_equal(splev([0, 4], tck, ext=ext), rstl[ext])
+
+        assert_raises(ValueError, splev, [0, 4], tck, ext=2)
+
+
+class TestSplder:
+    def setup_method(self):
+        # non-uniform grid, just to make it sure
+        x = np.linspace(0, 1, 100)**3
+        y = np.sin(20 * x)
+        self.spl = splrep(x, y)
+
+        # double check that knots are non-uniform
+        assert_(np.ptp(np.diff(self.spl[0])) > 0)
+
+    def test_inverse(self):
+        # Check that antiderivative + derivative is identity.
+        for n in range(5):
+            spl2 = splantider(self.spl, n)
+            spl3 = splder(spl2, n)
+            assert_allclose(self.spl[0], spl3[0])
+            assert_allclose(self.spl[1], spl3[1])
+            assert_equal(self.spl[2], spl3[2])
+
+    def test_splder_vs_splev(self):
+        # Check derivative vs. FITPACK
+
+        for n in range(3+1):
+            # Also extrapolation!
+            xx = np.linspace(-1, 2, 2000)
+            if n == 3:
+                # ... except that FITPACK extrapolates strangely for
+                # order 0, so let's not check that.
+                xx = xx[(xx >= 0) & (xx <= 1)]
+
+            dy = splev(xx, self.spl, n)
+            spl2 = splder(self.spl, n)
+            dy2 = splev(xx, spl2)
+            if n == 1:
+                assert_allclose(dy, dy2, rtol=2e-6)
+            else:
+                assert_allclose(dy, dy2)
+
+    def test_splantider_vs_splint(self):
+        # Check antiderivative vs. FITPACK
+        spl2 = splantider(self.spl)
+
+        # no extrapolation, splint assumes function is zero outside
+        # range
+        xx = np.linspace(0, 1, 20)
+
+        for x1 in xx:
+            for x2 in xx:
+                y1 = splint(x1, x2, self.spl)
+                y2 = splev(x2, spl2) - splev(x1, spl2)
+                assert_allclose(y1, y2)
+
+    def test_order0_diff(self):
+        assert_raises(ValueError, splder, self.spl, 4)
+
+    def test_kink(self):
+        # Should refuse to differentiate splines with kinks
+
+        spl2 = insert(0.5, self.spl, m=2)
+        splder(spl2, 2)  # Should work
+        assert_raises(ValueError, splder, spl2, 3)
+
+        spl2 = insert(0.5, self.spl, m=3)
+        splder(spl2, 1)  # Should work
+        assert_raises(ValueError, splder, spl2, 2)
+
+        spl2 = insert(0.5, self.spl, m=4)
+        assert_raises(ValueError, splder, spl2, 1)
+
+    def test_multidim(self):
+        # c can have trailing dims
+        for n in range(3):
+            t, c, k = self.spl
+            c2 = np.c_[c, c, c]
+            c2 = np.dstack((c2, c2))
+
+            spl2 = splantider((t, c2, k), n)
+            spl3 = splder(spl2, n)
+
+            assert_allclose(t, spl3[0])
+            assert_allclose(c2, spl3[1])
+            assert_equal(k, spl3[2])
+
+
+class TestSplint:
+    def test_len_c(self):
+        n, k = 7, 3
+        x = np.arange(n)
+        y = x**3
+        t, c, k = splrep(x, y, s=0)
+
+        # note that len(c) == len(t) == 11 (== len(x) + 2*(k-1))
+        assert len(t) == len(c) == n + 2*(k-1)
+
+        # integrate directly: $\int_0^6 x^3 dx = 6^4 / 4$
+        res = splint(0, 6, (t, c, k))
+        assert_allclose(res, 6**4 / 4, atol=1e-15)
+
+        # check that the coefficients past len(t) - k - 1 are ignored
+        c0 = c.copy()
+        c0[len(t)-k-1:] = np.nan
+        res0 = splint(0, 6, (t, c0, k))
+        assert_allclose(res0, 6**4 / 4, atol=1e-15)
+
+        # however, all other coefficients *are* used
+        c0[6] = np.nan
+        assert np.isnan(splint(0, 6, (t, c0, k)))
+
+        # check that the coefficient array can have length `len(t) - k - 1`
+        c1 = c[:len(t) - k - 1]
+        res1 = splint(0, 6, (t, c1, k))
+        assert_allclose(res1, 6**4 / 4, atol=1e-15)
+
+        # however shorter c arrays raise. The error from f2py is a
+        # `dftipack.error`, which is an Exception but not ValueError etc.
+        with assert_raises(Exception, match=r">=n-k-1"):
+            splint(0, 1, (np.ones(10), np.ones(5), 3))
+
+
+class TestBisplrep:
+    def test_overflow(self):
+        from numpy.lib.stride_tricks import as_strided
+        if dfitpack_int.itemsize == 8:
+            size = 1500000**2
+        else:
+            size = 400**2
+        # Don't allocate a real array, as it's very big, but rely
+        # on that it's not referenced
+        x = as_strided(np.zeros(()), shape=(size,))
+        assert_raises(OverflowError, bisplrep, x, x, x, w=x,
+                      xb=0, xe=1, yb=0, ye=1, s=0)
+
+    def test_regression_1310(self):
+        # Regression test for gh-1310
+        with np.load(data_file('bug-1310.npz')) as loaded_data:
+            data = loaded_data['data']
+
+        # Shouldn't crash -- the input data triggers work array sizes
+        # that caused previously some data to not be aligned on
+        # sizeof(double) boundaries in memory, which made the Fortran
+        # code to crash when compiled with -O3
+        bisplrep(data[:,0], data[:,1], data[:,2], kx=3, ky=3, s=0,
+                 full_output=True)
+
+    @pytest.mark.skipif(dfitpack_int != np.int64, reason="needs ilp64 fitpack")
+    def test_ilp64_bisplrep(self):
+        check_free_memory(28000)  # VM size, doesn't actually use the pages
+        x = np.linspace(0, 1, 400)
+        y = np.linspace(0, 1, 400)
+        x, y = np.meshgrid(x, y)
+        z = np.zeros_like(x)
+        tck = bisplrep(x, y, z, kx=3, ky=3, s=0)
+        assert_allclose(bisplev(0.5, 0.5, tck), 0.0)
+
+
+def test_dblint():
+    # Basic test to see it runs and gives the correct result on a trivial
+    # problem. Note that `dblint` is not exposed in the interpolate namespace.
+    x = np.linspace(0, 1)
+    y = np.linspace(0, 1)
+    xx, yy = np.meshgrid(x, y)
+    rect = RectBivariateSpline(x, y, 4 * xx * yy)
+    tck = list(rect.tck)
+    tck.extend(rect.degrees)
+
+    assert_almost_equal(dblint(0, 1, 0, 1, tck), 1)
+    assert_almost_equal(dblint(0, 0.5, 0, 1, tck), 0.25)
+    assert_almost_equal(dblint(0.5, 1, 0, 1, tck), 0.75)
+    assert_almost_equal(dblint(-100, 100, -100, 100, tck), 1)
+
+
+def test_splev_der_k():
+    # regression test for gh-2188: splev(x, tck, der=k) gives garbage or crashes
+    # for x outside of knot range
+
+    # test case from gh-2188
+    tck = (np.array([0., 0., 2.5, 2.5]),
+           np.array([-1.56679978, 2.43995873, 0., 0.]),
+           1)
+    t, c, k = tck
+    x = np.array([-3, 0, 2.5, 3])
+
+    # an explicit form of the linear spline
+    assert_allclose(splev(x, tck), c[0] + (c[1] - c[0]) * x/t[2])
+    assert_allclose(splev(x, tck, 1), (c[1]-c[0]) / t[2])
+
+    # now check a random spline vs splder
+    np.random.seed(1234)
+    x = np.sort(np.random.random(30))
+    y = np.random.random(30)
+    t, c, k = splrep(x, y)
+
+    x = [t[0] - 1., t[-1] + 1.]
+    tck2 = splder((t, c, k), k)
+    assert_allclose(splev(x, (t, c, k), k), splev(x, tck2))
+
+
+def test_splprep_segfault():
+    # regression test for gh-3847: splprep segfaults if knots are specified
+    # for task=-1
+    t = np.arange(0, 1.1, 0.1)
+    x = np.sin(2*np.pi*t)
+    y = np.cos(2*np.pi*t)
+    tck, u = splprep([x, y], s=0)
+    np.arange(0, 1.01, 0.01)
+
+    uknots = tck[0]  # using the knots from the previous fitting
+    tck, u = splprep([x, y], task=-1, t=uknots)  # here is the crash
+
+
+def test_bisplev_integer_overflow():
+    np.random.seed(1)
+
+    x = np.linspace(0, 1, 11)
+    y = x
+    z = np.random.randn(11, 11).ravel()
+    kx = 1
+    ky = 1
+
+    nx, tx, ny, ty, c, fp, ier = regrid_smth(
+        x, y, z, None, None, None, None, kx=kx, ky=ky, s=0.0)
+    tck = (tx[:nx], ty[:ny], c[:(nx - kx - 1) * (ny - ky - 1)], kx, ky)
+
+    xp = np.zeros([2621440])
+    yp = np.zeros([2621440])
+
+    assert_raises((RuntimeError, MemoryError), bisplev, xp, yp, tck)
+
+
+@pytest.mark.xslow
+def test_gh_1766():
+    # this should fail gracefully instead of segfaulting (int overflow)
+    size = 22
+    kx, ky = 3, 3
+    def f2(x, y):
+        return np.sin(x+y)
+
+    x = np.linspace(0, 10, size)
+    y = np.linspace(50, 700, size)
+    xy = makepairs(x, y)
+    tck = bisplrep(xy[0], xy[1], f2(xy[0], xy[1]), s=0, kx=kx, ky=ky)
+    # the size value here can either segfault
+    # or produce a MemoryError on main
+    tx_ty_size = 500000
+    tck[0] = np.arange(tx_ty_size)
+    tck[1] = np.arange(tx_ty_size) * 4
+    tt_0 = np.arange(50)
+    tt_1 = np.arange(50) * 3
+    with pytest.raises(MemoryError):
+        bisplev(tt_0, tt_1, tck, 1, 1)
+
+
+def test_spalde_scalar_input():
+    # Ticket #629
+    x = np.linspace(0, 10)
+    y = x**3
+    tck = splrep(x, y, k=3, t=[5])
+    res = spalde(np.float64(1), tck)
+    des = np.array([1., 3., 6., 6.])
+    assert_almost_equal(res, des)
+
+
+def test_spalde_nc():
+    # regression test for https://github.com/scipy/scipy/issues/19002
+    # here len(t) = 29 and len(c) = 25 (== len(t) - k - 1) 
+    x = np.asarray([-10., -9., -8., -7., -6., -5., -4., -3., -2.5, -2., -1.5,
+                    -1., -0.5, 0., 0.5, 1., 1.5, 2., 2.5, 3., 4., 5., 6.],
+                    dtype="float")
+    t = [-10.0, -10.0, -10.0, -10.0, -9.0, -8.0, -7.0, -6.0, -5.0, -4.0, -3.0,
+         -2.5, -2.0, -1.5, -1.0, -0.5, 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0,
+         5.0, 6.0, 6.0, 6.0, 6.0]
+    c = np.asarray([1., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
+                    0., 0., 0., 0., 0., 0., 0., 0., 0., 0.])
+    k = 3
+
+    res = spalde(x, (t, c, k))
+    res_splev = np.asarray([splev(x, (t, c, k), nu) for nu in range(4)])
+    assert_allclose(res, res_splev.T, atol=1e-15)

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_gil.py

@@ -0,0 +1,65 @@
+import itertools
+import threading
+import time
+
+import numpy as np
+from numpy.testing import assert_equal
+import pytest
+import scipy.interpolate
+
+
+class TestGIL:
+    """Check if the GIL is properly released by scipy.interpolate functions."""
+
+    def setup_method(self):
+        self.messages = []
+
+    def log(self, message):
+        self.messages.append(message)
+
+    def make_worker_thread(self, target, args):
+        log = self.log
+
+        class WorkerThread(threading.Thread):
+            def run(self):
+                log('interpolation started')
+                target(*args)
+                log('interpolation complete')
+
+        return WorkerThread()
+
+    @pytest.mark.xslow
+    @pytest.mark.xfail(reason='race conditions, may depend on system load')
+    def test_rectbivariatespline(self):
+        def generate_params(n_points):
+            x = y = np.linspace(0, 1000, n_points)
+            x_grid, y_grid = np.meshgrid(x, y)
+            z = x_grid * y_grid
+            return x, y, z
+
+        def calibrate_delay(requested_time):
+            for n_points in itertools.count(5000, 1000):
+                args = generate_params(n_points)
+                time_started = time.time()
+                interpolate(*args)
+                if time.time() - time_started > requested_time:
+                    return args
+
+        def interpolate(x, y, z):
+            scipy.interpolate.RectBivariateSpline(x, y, z)
+
+        args = calibrate_delay(requested_time=3)
+        worker_thread = self.make_worker_thread(interpolate, args)
+        worker_thread.start()
+        for i in range(3):
+            time.sleep(0.5)
+            self.log('working')
+        worker_thread.join()
+        assert_equal(self.messages, [
+            'interpolation started',
+            'working',
+            'working',
+            'working',
+            'interpolation complete',
+        ])
+

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_interpnd.py

@@ -0,0 +1,436 @@
+import os
+import sys
+
+import numpy as np
+from numpy.testing import (assert_equal, assert_allclose, assert_almost_equal,
+                           suppress_warnings)
+from pytest import raises as assert_raises
+import pytest
+
+from scipy._lib._testutils import check_free_memory
+import scipy.interpolate.interpnd as interpnd
+import scipy.spatial._qhull as qhull
+
+import pickle
+import threading
+
+_IS_32BIT = (sys.maxsize < 2**32)
+
+
+def data_file(basename):
+    return os.path.join(os.path.abspath(os.path.dirname(__file__)),
+                        'data', basename)
+
+
+class TestLinearNDInterpolation:
+    def test_smoketest(self):
+        # Test at single points
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+
+        yi = interpnd.LinearNDInterpolator(x, y)(x)
+        assert_almost_equal(y, yi)
+
+    def test_smoketest_alternate(self):
+        # Test at single points, alternate calling convention
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+
+        yi = interpnd.LinearNDInterpolator((x[:,0], x[:,1]), y)(x[:,0], x[:,1])
+        assert_almost_equal(y, yi)
+
+    def test_complex_smoketest(self):
+        # Test at single points
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        yi = interpnd.LinearNDInterpolator(x, y)(x)
+        assert_almost_equal(y, yi)
+
+    def test_tri_input(self):
+        # Test at single points
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        yi = interpnd.LinearNDInterpolator(tri, y)(x)
+        assert_almost_equal(y, yi)
+
+    def test_square(self):
+        # Test barycentric interpolation on a square against a manual
+        # implementation
+
+        points = np.array([(0,0), (0,1), (1,1), (1,0)], dtype=np.float64)
+        values = np.array([1., 2., -3., 5.], dtype=np.float64)
+
+        # NB: assume triangles (0, 1, 3) and (1, 2, 3)
+        #
+        #  1----2
+        #  | \  |
+        #  |  \ |
+        #  0----3
+
+        def ip(x, y):
+            t1 = (x + y <= 1)
+            t2 = ~t1
+
+            x1 = x[t1]
+            y1 = y[t1]
+
+            x2 = x[t2]
+            y2 = y[t2]
+
+            z = 0*x
+
+            z[t1] = (values[0]*(1 - x1 - y1)
+                     + values[1]*y1
+                     + values[3]*x1)
+
+            z[t2] = (values[2]*(x2 + y2 - 1)
+                     + values[1]*(1 - x2)
+                     + values[3]*(1 - y2))
+            return z
+
+        xx, yy = np.broadcast_arrays(np.linspace(0, 1, 14)[:,None],
+                                     np.linspace(0, 1, 14)[None,:])
+        xx = xx.ravel()
+        yy = yy.ravel()
+
+        xi = np.array([xx, yy]).T.copy()
+        zi = interpnd.LinearNDInterpolator(points, values)(xi)
+
+        assert_almost_equal(zi, ip(xx, yy))
+
+    def test_smoketest_rescale(self):
+        # Test at single points
+        x = np.array([(0, 0), (-5, -5), (-5, 5), (5, 5), (2.5, 3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+
+        yi = interpnd.LinearNDInterpolator(x, y, rescale=True)(x)
+        assert_almost_equal(y, yi)
+
+    def test_square_rescale(self):
+        # Test barycentric interpolation on a rectangle with rescaling
+        # agaings the same implementation without rescaling
+
+        points = np.array([(0,0), (0,100), (10,100), (10,0)], dtype=np.float64)
+        values = np.array([1., 2., -3., 5.], dtype=np.float64)
+
+        xx, yy = np.broadcast_arrays(np.linspace(0, 10, 14)[:,None],
+                                     np.linspace(0, 100, 14)[None,:])
+        xx = xx.ravel()
+        yy = yy.ravel()
+        xi = np.array([xx, yy]).T.copy()
+        zi = interpnd.LinearNDInterpolator(points, values)(xi)
+        zi_rescaled = interpnd.LinearNDInterpolator(points, values,
+                rescale=True)(xi)
+
+        assert_almost_equal(zi, zi_rescaled)
+
+    def test_tripoints_input_rescale(self):
+        # Test at single points
+        x = np.array([(0,0), (-5,-5), (-5,5), (5, 5), (2.5, 3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        yi = interpnd.LinearNDInterpolator(tri.points, y)(x)
+        yi_rescale = interpnd.LinearNDInterpolator(tri.points, y,
+                rescale=True)(x)
+        assert_almost_equal(yi, yi_rescale)
+
+    def test_tri_input_rescale(self):
+        # Test at single points
+        x = np.array([(0,0), (-5,-5), (-5,5), (5, 5), (2.5, 3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        match = ("Rescaling is not supported when passing a "
+                 "Delaunay triangulation as ``points``.")
+        with pytest.raises(ValueError, match=match):
+            interpnd.LinearNDInterpolator(tri, y, rescale=True)(x)
+
+    def test_pickle(self):
+        # Test at single points
+        np.random.seed(1234)
+        x = np.random.rand(30, 2)
+        y = np.random.rand(30) + 1j*np.random.rand(30)
+
+        ip = interpnd.LinearNDInterpolator(x, y)
+        ip2 = pickle.loads(pickle.dumps(ip))
+
+        assert_almost_equal(ip(0.5, 0.5), ip2(0.5, 0.5))
+
+    @pytest.mark.slow
+    @pytest.mark.skipif(_IS_32BIT, reason='it fails on 32-bit')
+    def test_threading(self):
+        # This test was taken from issue 8856
+        # https://github.com/scipy/scipy/issues/8856
+        check_free_memory(10000)
+
+        r_ticks = np.arange(0, 4200, 10)
+        phi_ticks = np.arange(0, 4200, 10)
+        r_grid, phi_grid = np.meshgrid(r_ticks, phi_ticks)
+
+        def do_interp(interpolator, slice_rows, slice_cols):
+            grid_x, grid_y = np.mgrid[slice_rows, slice_cols]
+            res = interpolator((grid_x, grid_y))
+            return res
+
+        points = np.vstack((r_grid.ravel(), phi_grid.ravel())).T
+        values = (r_grid * phi_grid).ravel()
+        interpolator = interpnd.LinearNDInterpolator(points, values)
+
+        worker_thread_1 = threading.Thread(
+            target=do_interp,
+            args=(interpolator, slice(0, 2100), slice(0, 2100)))
+        worker_thread_2 = threading.Thread(
+            target=do_interp,
+            args=(interpolator, slice(2100, 4200), slice(0, 2100)))
+        worker_thread_3 = threading.Thread(
+            target=do_interp,
+            args=(interpolator, slice(0, 2100), slice(2100, 4200)))
+        worker_thread_4 = threading.Thread(
+            target=do_interp,
+            args=(interpolator, slice(2100, 4200), slice(2100, 4200)))
+
+        worker_thread_1.start()
+        worker_thread_2.start()
+        worker_thread_3.start()
+        worker_thread_4.start()
+
+        worker_thread_1.join()
+        worker_thread_2.join()
+        worker_thread_3.join()
+        worker_thread_4.join()
+
+
+class TestEstimateGradients2DGlobal:
+    def test_smoketest(self):
+        x = np.array([(0, 0), (0, 2),
+                      (1, 0), (1, 2), (0.25, 0.75), (0.6, 0.8)], dtype=float)
+        tri = qhull.Delaunay(x)
+
+        # Should be exact for linear functions, independent of triangulation
+
+        funcs = [
+            (lambda x, y: 0*x + 1, (0, 0)),
+            (lambda x, y: 0 + x, (1, 0)),
+            (lambda x, y: -2 + y, (0, 1)),
+            (lambda x, y: 3 + 3*x + 14.15*y, (3, 14.15))
+        ]
+
+        for j, (func, grad) in enumerate(funcs):
+            z = func(x[:,0], x[:,1])
+            dz = interpnd.estimate_gradients_2d_global(tri, z, tol=1e-6)
+
+            assert_equal(dz.shape, (6, 2))
+            assert_allclose(dz, np.array(grad)[None,:] + 0*dz,
+                            rtol=1e-5, atol=1e-5, err_msg="item %d" % j)
+
+    def test_regression_2359(self):
+        # Check regression --- for certain point sets, gradient
+        # estimation could end up in an infinite loop
+        points = np.load(data_file('estimate_gradients_hang.npy'))
+        values = np.random.rand(points.shape[0])
+        tri = qhull.Delaunay(points)
+
+        # This should not hang
+        with suppress_warnings() as sup:
+            sup.filter(interpnd.GradientEstimationWarning,
+                       "Gradient estimation did not converge")
+            interpnd.estimate_gradients_2d_global(tri, values, maxiter=1)
+
+
+class TestCloughTocher2DInterpolator:
+
+    def _check_accuracy(self, func, x=None, tol=1e-6, alternate=False,
+                        rescale=False, **kw):
+        np.random.seed(1234)
+        if x is None:
+            x = np.array([(0, 0), (0, 1),
+                          (1, 0), (1, 1), (0.25, 0.75), (0.6, 0.8),
+                          (0.5, 0.2)],
+                         dtype=float)
+
+        if not alternate:
+            ip = interpnd.CloughTocher2DInterpolator(x, func(x[:,0], x[:,1]),
+                                                     tol=1e-6, rescale=rescale)
+        else:
+            ip = interpnd.CloughTocher2DInterpolator((x[:,0], x[:,1]),
+                                                     func(x[:,0], x[:,1]),
+                                                     tol=1e-6, rescale=rescale)
+
+        p = np.random.rand(50, 2)
+
+        if not alternate:
+            a = ip(p)
+        else:
+            a = ip(p[:,0], p[:,1])
+        b = func(p[:,0], p[:,1])
+
+        try:
+            assert_allclose(a, b, **kw)
+        except AssertionError:
+            print("_check_accuracy: abs(a-b):", abs(a - b))
+            print("ip.grad:", ip.grad)
+            raise
+
+    def test_linear_smoketest(self):
+        # Should be exact for linear functions, independent of triangulation
+        funcs = [
+            lambda x, y: 0*x + 1,
+            lambda x, y: 0 + x,
+            lambda x, y: -2 + y,
+            lambda x, y: 3 + 3*x + 14.15*y,
+        ]
+
+        for j, func in enumerate(funcs):
+            self._check_accuracy(func, tol=1e-13, atol=1e-7, rtol=1e-7,
+                                 err_msg="Function %d" % j)
+            self._check_accuracy(func, tol=1e-13, atol=1e-7, rtol=1e-7,
+                                 alternate=True,
+                                 err_msg="Function (alternate) %d" % j)
+            # check rescaling
+            self._check_accuracy(func, tol=1e-13, atol=1e-7, rtol=1e-7,
+                                 err_msg="Function (rescaled) %d" % j, rescale=True)
+            self._check_accuracy(func, tol=1e-13, atol=1e-7, rtol=1e-7,
+                                 alternate=True, rescale=True,
+                                 err_msg="Function (alternate, rescaled) %d" % j)
+
+    def test_quadratic_smoketest(self):
+        # Should be reasonably accurate for quadratic functions
+        funcs = [
+            lambda x, y: x**2,
+            lambda x, y: y**2,
+            lambda x, y: x**2 - y**2,
+            lambda x, y: x*y,
+        ]
+
+        for j, func in enumerate(funcs):
+            self._check_accuracy(func, tol=1e-9, atol=0.22, rtol=0,
+                                 err_msg="Function %d" % j)
+            self._check_accuracy(func, tol=1e-9, atol=0.22, rtol=0,
+                                 err_msg="Function %d" % j, rescale=True)
+
+    def test_tri_input(self):
+        # Test at single points
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        yi = interpnd.CloughTocher2DInterpolator(tri, y)(x)
+        assert_almost_equal(y, yi)
+
+    def test_tri_input_rescale(self):
+        # Test at single points
+        x = np.array([(0,0), (-5,-5), (-5,5), (5, 5), (2.5, 3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        match = ("Rescaling is not supported when passing a "
+                 "Delaunay triangulation as ``points``.")
+        with pytest.raises(ValueError, match=match):
+            interpnd.CloughTocher2DInterpolator(tri, y, rescale=True)(x)
+
+    def test_tripoints_input_rescale(self):
+        # Test at single points
+        x = np.array([(0,0), (-5,-5), (-5,5), (5, 5), (2.5, 3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 3j*y
+
+        tri = qhull.Delaunay(x)
+        yi = interpnd.CloughTocher2DInterpolator(tri.points, y)(x)
+        yi_rescale = interpnd.CloughTocher2DInterpolator(tri.points, y, rescale=True)(x)
+        assert_almost_equal(yi, yi_rescale)
+
+    @pytest.mark.fail_slow(2)
+    def test_dense(self):
+        # Should be more accurate for dense meshes
+        funcs = [
+            lambda x, y: x**2,
+            lambda x, y: y**2,
+            lambda x, y: x**2 - y**2,
+            lambda x, y: x*y,
+            lambda x, y: np.cos(2*np.pi*x)*np.sin(2*np.pi*y)
+        ]
+
+        np.random.seed(4321)  # use a different seed than the check!
+        grid = np.r_[np.array([(0,0), (0,1), (1,0), (1,1)], dtype=float),
+                     np.random.rand(30*30, 2)]
+
+        for j, func in enumerate(funcs):
+            self._check_accuracy(func, x=grid, tol=1e-9, atol=5e-3, rtol=1e-2,
+                                 err_msg="Function %d" % j)
+            self._check_accuracy(func, x=grid, tol=1e-9, atol=5e-3, rtol=1e-2,
+                                 err_msg="Function %d" % j, rescale=True)
+
+    def test_wrong_ndim(self):
+        x = np.random.randn(30, 3)
+        y = np.random.randn(30)
+        assert_raises(ValueError, interpnd.CloughTocher2DInterpolator, x, y)
+
+    def test_pickle(self):
+        # Test at single points
+        np.random.seed(1234)
+        x = np.random.rand(30, 2)
+        y = np.random.rand(30) + 1j*np.random.rand(30)
+
+        ip = interpnd.CloughTocher2DInterpolator(x, y)
+        ip2 = pickle.loads(pickle.dumps(ip))
+
+        assert_almost_equal(ip(0.5, 0.5), ip2(0.5, 0.5))
+
+    def test_boundary_tri_symmetry(self):
+        # Interpolation at neighbourless triangles should retain
+        # symmetry with mirroring the triangle.
+
+        # Equilateral triangle
+        points = np.array([(0, 0), (1, 0), (0.5, np.sqrt(3)/2)])
+        values = np.array([1, 0, 0])
+
+        ip = interpnd.CloughTocher2DInterpolator(points, values)
+
+        # Set gradient to zero at vertices
+        ip.grad[...] = 0
+
+        # Interpolation should be symmetric vs. bisector
+        alpha = 0.3
+        p1 = np.array([0.5 * np.cos(alpha), 0.5 * np.sin(alpha)])
+        p2 = np.array([0.5 * np.cos(np.pi/3 - alpha), 0.5 * np.sin(np.pi/3 - alpha)])
+
+        v1 = ip(p1)
+        v2 = ip(p2)
+        assert_allclose(v1, v2)
+
+        # ... and affine invariant
+        np.random.seed(1)
+        A = np.random.randn(2, 2)
+        b = np.random.randn(2)
+
+        points = A.dot(points.T).T + b[None,:]
+        p1 = A.dot(p1) + b
+        p2 = A.dot(p2) + b
+
+        ip = interpnd.CloughTocher2DInterpolator(points, values)
+        ip.grad[...] = 0
+
+        w1 = ip(p1)
+        w2 = ip(p2)
+        assert_allclose(w1, v1)
+        assert_allclose(w2, v2)

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_ndgriddata.py

@@ -0,0 +1,284 @@
+import numpy as np
+from numpy.testing import assert_equal, assert_array_equal, assert_allclose
+import pytest
+from pytest import raises as assert_raises
+
+from scipy.interpolate import (griddata, NearestNDInterpolator,
+                               LinearNDInterpolator,
+                               CloughTocher2DInterpolator)
+
+
+parametrize_interpolators = pytest.mark.parametrize(
+    "interpolator", [NearestNDInterpolator, LinearNDInterpolator,
+                     CloughTocher2DInterpolator]
+)
+
+class TestGriddata:
+    def test_fill_value(self):
+        x = [(0,0), (0,1), (1,0)]
+        y = [1, 2, 3]
+
+        yi = griddata(x, y, [(1,1), (1,2), (0,0)], fill_value=-1)
+        assert_array_equal(yi, [-1., -1, 1])
+
+        yi = griddata(x, y, [(1,1), (1,2), (0,0)])
+        assert_array_equal(yi, [np.nan, np.nan, 1])
+
+    def test_alternative_call(self):
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = (np.arange(x.shape[0], dtype=np.float64)[:,None]
+             + np.array([0,1])[None,:])
+
+        for method in ('nearest', 'linear', 'cubic'):
+            for rescale in (True, False):
+                msg = repr((method, rescale))
+                yi = griddata((x[:,0], x[:,1]), y, (x[:,0], x[:,1]), method=method,
+                              rescale=rescale)
+                assert_allclose(y, yi, atol=1e-14, err_msg=msg)
+
+    def test_multivalue_2d(self):
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = (np.arange(x.shape[0], dtype=np.float64)[:,None]
+             + np.array([0,1])[None,:])
+
+        for method in ('nearest', 'linear', 'cubic'):
+            for rescale in (True, False):
+                msg = repr((method, rescale))
+                yi = griddata(x, y, x, method=method, rescale=rescale)
+                assert_allclose(y, yi, atol=1e-14, err_msg=msg)
+
+    def test_multipoint_2d(self):
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+
+        xi = x[:,None,:] + np.array([0,0,0])[None,:,None]
+
+        for method in ('nearest', 'linear', 'cubic'):
+            for rescale in (True, False):
+                msg = repr((method, rescale))
+                yi = griddata(x, y, xi, method=method, rescale=rescale)
+
+                assert_equal(yi.shape, (5, 3), err_msg=msg)
+                assert_allclose(yi, np.tile(y[:,None], (1, 3)),
+                                atol=1e-14, err_msg=msg)
+
+    def test_complex_2d(self):
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 2j*y[::-1]
+
+        xi = x[:,None,:] + np.array([0,0,0])[None,:,None]
+
+        for method in ('nearest', 'linear', 'cubic'):
+            for rescale in (True, False):
+                msg = repr((method, rescale))
+                yi = griddata(x, y, xi, method=method, rescale=rescale)
+
+                assert_equal(yi.shape, (5, 3), err_msg=msg)
+                assert_allclose(yi, np.tile(y[:,None], (1, 3)),
+                                atol=1e-14, err_msg=msg)
+
+    def test_1d(self):
+        x = np.array([1, 2.5, 3, 4.5, 5, 6])
+        y = np.array([1, 2, 0, 3.9, 2, 1])
+
+        for method in ('nearest', 'linear', 'cubic'):
+            assert_allclose(griddata(x, y, x, method=method), y,
+                            err_msg=method, atol=1e-14)
+            assert_allclose(griddata(x.reshape(6, 1), y, x, method=method), y,
+                            err_msg=method, atol=1e-14)
+            assert_allclose(griddata((x,), y, (x,), method=method), y,
+                            err_msg=method, atol=1e-14)
+
+    def test_1d_borders(self):
+        # Test for nearest neighbor case with xi outside
+        # the range of the values.
+        x = np.array([1, 2.5, 3, 4.5, 5, 6])
+        y = np.array([1, 2, 0, 3.9, 2, 1])
+        xi = np.array([0.9, 6.5])
+        yi_should = np.array([1.0, 1.0])
+
+        method = 'nearest'
+        assert_allclose(griddata(x, y, xi,
+                                 method=method), yi_should,
+                        err_msg=method,
+                        atol=1e-14)
+        assert_allclose(griddata(x.reshape(6, 1), y, xi,
+                                 method=method), yi_should,
+                        err_msg=method,
+                        atol=1e-14)
+        assert_allclose(griddata((x, ), y, (xi, ),
+                                 method=method), yi_should,
+                        err_msg=method,
+                        atol=1e-14)
+
+    def test_1d_unsorted(self):
+        x = np.array([2.5, 1, 4.5, 5, 6, 3])
+        y = np.array([1, 2, 0, 3.9, 2, 1])
+
+        for method in ('nearest', 'linear', 'cubic'):
+            assert_allclose(griddata(x, y, x, method=method), y,
+                            err_msg=method, atol=1e-10)
+            assert_allclose(griddata(x.reshape(6, 1), y, x, method=method), y,
+                            err_msg=method, atol=1e-10)
+            assert_allclose(griddata((x,), y, (x,), method=method), y,
+                            err_msg=method, atol=1e-10)
+
+    def test_square_rescale_manual(self):
+        points = np.array([(0,0), (0,100), (10,100), (10,0), (1, 5)], dtype=np.float64)
+        points_rescaled = np.array([(0,0), (0,1), (1,1), (1,0), (0.1, 0.05)],
+                                   dtype=np.float64)
+        values = np.array([1., 2., -3., 5., 9.], dtype=np.float64)
+
+        xx, yy = np.broadcast_arrays(np.linspace(0, 10, 14)[:,None],
+                                     np.linspace(0, 100, 14)[None,:])
+        xx = xx.ravel()
+        yy = yy.ravel()
+        xi = np.array([xx, yy]).T.copy()
+
+        for method in ('nearest', 'linear', 'cubic'):
+            msg = method
+            zi = griddata(points_rescaled, values, xi/np.array([10, 100.]),
+                          method=method)
+            zi_rescaled = griddata(points, values, xi, method=method,
+                                   rescale=True)
+            assert_allclose(zi, zi_rescaled, err_msg=msg,
+                            atol=1e-12)
+
+    def test_xi_1d(self):
+        # Check that 1-D xi is interpreted as a coordinate
+        x = np.array([(0,0), (-0.5,-0.5), (-0.5,0.5), (0.5, 0.5), (0.25, 0.3)],
+                     dtype=np.float64)
+        y = np.arange(x.shape[0], dtype=np.float64)
+        y = y - 2j*y[::-1]
+
+        xi = np.array([0.5, 0.5])
+
+        for method in ('nearest', 'linear', 'cubic'):
+            p1 = griddata(x, y, xi, method=method)
+            p2 = griddata(x, y, xi[None,:], method=method)
+            assert_allclose(p1, p2, err_msg=method)
+
+            xi1 = np.array([0.5])
+            xi3 = np.array([0.5, 0.5, 0.5])
+            assert_raises(ValueError, griddata, x, y, xi1,
+                          method=method)
+            assert_raises(ValueError, griddata, x, y, xi3,
+                          method=method)
+
+
+class TestNearestNDInterpolator:
+    def test_nearest_options(self):
+        # smoke test that NearestNDInterpolator accept cKDTree options
+        npts, nd = 4, 3
+        x = np.arange(npts*nd).reshape((npts, nd))
+        y = np.arange(npts)
+        nndi = NearestNDInterpolator(x, y)
+
+        opts = {'balanced_tree': False, 'compact_nodes': False}
+        nndi_o = NearestNDInterpolator(x, y, tree_options=opts)
+        assert_allclose(nndi(x), nndi_o(x), atol=1e-14)
+
+    def test_nearest_list_argument(self):
+        nd = np.array([[0, 0, 0, 0, 1, 0, 1],
+                       [0, 0, 0, 0, 0, 1, 1],
+                       [0, 0, 0, 0, 1, 1, 2]])
+        d = nd[:, 3:]
+
+        # z is np.array
+        NI = NearestNDInterpolator((d[0], d[1]), d[2])
+        assert_array_equal(NI([0.1, 0.9], [0.1, 0.9]), [0, 2])
+
+        # z is list
+        NI = NearestNDInterpolator((d[0], d[1]), list(d[2]))
+        assert_array_equal(NI([0.1, 0.9], [0.1, 0.9]), [0, 2])
+
+    def test_nearest_query_options(self):
+        nd = np.array([[0, 0.5, 0, 1],
+                       [0, 0, 0.5, 1],
+                       [0, 1, 1, 2]])
+        delta = 0.1
+        query_points = [0 + delta, 1 + delta], [0 + delta, 1 + delta]
+
+        # case 1 - query max_dist is smaller than
+        # the query points' nearest distance to nd.
+        NI = NearestNDInterpolator((nd[0], nd[1]), nd[2])
+        distance_upper_bound = np.sqrt(delta ** 2 + delta ** 2) - 1e-7
+        assert_array_equal(NI(query_points, distance_upper_bound=distance_upper_bound),
+                           [np.nan, np.nan])
+
+        # case 2 - query p is inf, will return [0, 2]
+        distance_upper_bound = np.sqrt(delta ** 2 + delta ** 2) - 1e-7
+        p = np.inf
+        assert_array_equal(
+            NI(query_points, distance_upper_bound=distance_upper_bound, p=p),
+            [0, 2]
+        )
+
+        # case 3 - query max_dist is larger, so should return non np.nan
+        distance_upper_bound = np.sqrt(delta ** 2 + delta ** 2) + 1e-7
+        assert_array_equal(
+            NI(query_points, distance_upper_bound=distance_upper_bound),
+            [0, 2]
+        )
+
+    def test_nearest_query_valid_inputs(self):
+        nd = np.array([[0, 1, 0, 1],
+                       [0, 0, 1, 1],
+                       [0, 1, 1, 2]])
+        NI = NearestNDInterpolator((nd[0], nd[1]), nd[2])
+        with assert_raises(TypeError):
+            NI([0.5, 0.5], query_options="not a dictionary")
+
+
+class TestNDInterpolators:
+    @parametrize_interpolators
+    def test_broadcastable_input(self, interpolator):
+        # input data
+        np.random.seed(0)
+        x = np.random.random(10)
+        y = np.random.random(10)
+        z = np.hypot(x, y)
+
+        # x-y grid for interpolation
+        X = np.linspace(min(x), max(x))
+        Y = np.linspace(min(y), max(y))
+        X, Y = np.meshgrid(X, Y)
+        XY = np.vstack((X.ravel(), Y.ravel())).T
+        interp = interpolator(list(zip(x, y)), z)
+        # single array input
+        interp_points0 = interp(XY)
+        # tuple input
+        interp_points1 = interp((X, Y))
+        interp_points2 = interp((X, 0.0))
+        # broadcastable input
+        interp_points3 = interp(X, Y)
+        interp_points4 = interp(X, 0.0)
+
+        assert_equal(interp_points0.size ==
+                     interp_points1.size ==
+                     interp_points2.size ==
+                     interp_points3.size ==
+                     interp_points4.size, True)
+
+    @parametrize_interpolators
+    def test_read_only(self, interpolator):
+        # input data
+        np.random.seed(0)
+        xy = np.random.random((10, 2))
+        x, y = xy[:, 0], xy[:, 1]
+        z = np.hypot(x, y)
+
+        # interpolation points
+        XY = np.random.random((50, 2))
+
+        xy.setflags(write=False)
+        z.setflags(write=False)
+        XY.setflags(write=False)
+
+        interp = interpolator(xy, z)
+        interp(XY)

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_pade.py

@@ -0,0 +1,104 @@
+from numpy.testing import (assert_array_equal, assert_array_almost_equal)
+from scipy.interpolate import pade
+
+def test_pade_trivial():
+    nump, denomp = pade([1.0], 0)
+    assert_array_equal(nump.c, [1.0])
+    assert_array_equal(denomp.c, [1.0])
+
+    nump, denomp = pade([1.0], 0, 0)
+    assert_array_equal(nump.c, [1.0])
+    assert_array_equal(denomp.c, [1.0])
+
+
+def test_pade_4term_exp():
+    # First four Taylor coefficients of exp(x).
+    # Unlike poly1d, the first array element is the zero-order term.
+    an = [1.0, 1.0, 0.5, 1.0/6]
+
+    nump, denomp = pade(an, 0)
+    assert_array_almost_equal(nump.c, [1.0/6, 0.5, 1.0, 1.0])
+    assert_array_almost_equal(denomp.c, [1.0])
+
+    nump, denomp = pade(an, 1)
+    assert_array_almost_equal(nump.c, [1.0/6, 2.0/3, 1.0])
+    assert_array_almost_equal(denomp.c, [-1.0/3, 1.0])
+
+    nump, denomp = pade(an, 2)
+    assert_array_almost_equal(nump.c, [1.0/3, 1.0])
+    assert_array_almost_equal(denomp.c, [1.0/6, -2.0/3, 1.0])
+
+    nump, denomp = pade(an, 3)
+    assert_array_almost_equal(nump.c, [1.0])
+    assert_array_almost_equal(denomp.c, [-1.0/6, 0.5, -1.0, 1.0])
+
+    # Testing inclusion of optional parameter
+    nump, denomp = pade(an, 0, 3)
+    assert_array_almost_equal(nump.c, [1.0/6, 0.5, 1.0, 1.0])
+    assert_array_almost_equal(denomp.c, [1.0])
+
+    nump, denomp = pade(an, 1, 2)
+    assert_array_almost_equal(nump.c, [1.0/6, 2.0/3, 1.0])
+    assert_array_almost_equal(denomp.c, [-1.0/3, 1.0])
+
+    nump, denomp = pade(an, 2, 1)
+    assert_array_almost_equal(nump.c, [1.0/3, 1.0])
+    assert_array_almost_equal(denomp.c, [1.0/6, -2.0/3, 1.0])
+
+    nump, denomp = pade(an, 3, 0)
+    assert_array_almost_equal(nump.c, [1.0])
+    assert_array_almost_equal(denomp.c, [-1.0/6, 0.5, -1.0, 1.0])
+
+    # Testing reducing array.
+    nump, denomp = pade(an, 0, 2)
+    assert_array_almost_equal(nump.c, [0.5, 1.0, 1.0])
+    assert_array_almost_equal(denomp.c, [1.0])
+
+    nump, denomp = pade(an, 1, 1)
+    assert_array_almost_equal(nump.c, [1.0/2, 1.0])
+    assert_array_almost_equal(denomp.c, [-1.0/2, 1.0])
+
+    nump, denomp = pade(an, 2, 0)
+    assert_array_almost_equal(nump.c, [1.0])
+    assert_array_almost_equal(denomp.c, [1.0/2, -1.0, 1.0])
+
+
+def test_pade_ints():
+    # Simple test sequences (one of ints, one of floats).
+    an_int = [1, 2, 3, 4]
+    an_flt = [1.0, 2.0, 3.0, 4.0]
+
+    # Make sure integer arrays give the same result as float arrays with same values.
+    for i in range(0, len(an_int)):
+        for j in range(0, len(an_int) - i):
+
+            # Create float and int pade approximation for given order.
+            nump_int, denomp_int = pade(an_int, i, j)
+            nump_flt, denomp_flt = pade(an_flt, i, j)
+
+            # Check that they are the same.
+            assert_array_equal(nump_int.c, nump_flt.c)
+            assert_array_equal(denomp_int.c, denomp_flt.c)
+
+
+def test_pade_complex():
+    # Test sequence with known solutions - see page 6 of 10.1109/PESGM.2012.6344759.
+    # Variable x is parameter - these tests will work with any complex number.
+    x = 0.2 + 0.6j
+    an = [1.0, x, -x*x.conjugate(), x.conjugate()*(x**2) + x*(x.conjugate()**2),
+          -(x**3)*x.conjugate() - 3*(x*x.conjugate())**2 - x*(x.conjugate()**3)]
+
+    nump, denomp = pade(an, 1, 1)
+    assert_array_almost_equal(nump.c, [x + x.conjugate(), 1.0])
+    assert_array_almost_equal(denomp.c, [x.conjugate(), 1.0])
+
+    nump, denomp = pade(an, 1, 2)
+    assert_array_almost_equal(nump.c, [x**2, 2*x + x.conjugate(), 1.0])
+    assert_array_almost_equal(denomp.c, [x + x.conjugate(), 1.0])
+
+    nump, denomp = pade(an, 2, 2)
+    assert_array_almost_equal(
+        nump.c,
+        [x**2 + x*x.conjugate() + x.conjugate()**2, 2*(x + x.conjugate()), 1.0]
+    )
+    assert_array_almost_equal(denomp.c, [x.conjugate()**2, x + 2*x.conjugate(), 1.0])

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_polyint.py

@@ -0,0 +1,941 @@
+import warnings
+import io
+import numpy as np
+
+from numpy.testing import (
+    assert_almost_equal, assert_array_equal, assert_array_almost_equal,
+    assert_allclose, assert_equal, assert_)
+from pytest import raises as assert_raises
+import pytest
+
+from scipy.interpolate import (
+    KroghInterpolator, krogh_interpolate,
+    BarycentricInterpolator, barycentric_interpolate,
+    approximate_taylor_polynomial, CubicHermiteSpline, pchip,
+    PchipInterpolator, pchip_interpolate, Akima1DInterpolator, CubicSpline,
+    make_interp_spline)
+
+
+def check_shape(interpolator_cls, x_shape, y_shape, deriv_shape=None, axis=0,
+                extra_args={}):
+    np.random.seed(1234)
+
+    x = [-1, 0, 1, 2, 3, 4]
+    s = list(range(1, len(y_shape)+1))
+    s.insert(axis % (len(y_shape)+1), 0)
+    y = np.random.rand(*((6,) + y_shape)).transpose(s)
+
+    xi = np.zeros(x_shape)
+    if interpolator_cls is CubicHermiteSpline:
+        dydx = np.random.rand(*((6,) + y_shape)).transpose(s)
+        yi = interpolator_cls(x, y, dydx, axis=axis, **extra_args)(xi)
+    else:
+        yi = interpolator_cls(x, y, axis=axis, **extra_args)(xi)
+
+    target_shape = ((deriv_shape or ()) + y.shape[:axis]
+                    + x_shape + y.shape[axis:][1:])
+    assert_equal(yi.shape, target_shape)
+
+    # check it works also with lists
+    if x_shape and y.size > 0:
+        if interpolator_cls is CubicHermiteSpline:
+            interpolator_cls(list(x), list(y), list(dydx), axis=axis,
+                             **extra_args)(list(xi))
+        else:
+            interpolator_cls(list(x), list(y), axis=axis,
+                             **extra_args)(list(xi))
+
+    # check also values
+    if xi.size > 0 and deriv_shape is None:
+        bs_shape = y.shape[:axis] + (1,)*len(x_shape) + y.shape[axis:][1:]
+        yv = y[((slice(None,),)*(axis % y.ndim)) + (1,)]
+        yv = yv.reshape(bs_shape)
+
+        yi, y = np.broadcast_arrays(yi, yv)
+        assert_allclose(yi, y)
+
+
+SHAPES = [(), (0,), (1,), (6, 2, 5)]
+
+
+def test_shapes():
+
+    def spl_interp(x, y, axis):
+        return make_interp_spline(x, y, axis=axis)
+
+    for ip in [KroghInterpolator, BarycentricInterpolator, CubicHermiteSpline,
+               pchip, Akima1DInterpolator, CubicSpline, spl_interp]:
+        for s1 in SHAPES:
+            for s2 in SHAPES:
+                for axis in range(-len(s2), len(s2)):
+                    if ip != CubicSpline:
+                        check_shape(ip, s1, s2, None, axis)
+                    else:
+                        for bc in ['natural', 'clamped']:
+                            extra = {'bc_type': bc}
+                            check_shape(ip, s1, s2, None, axis, extra)
+
+def test_derivs_shapes():
+    for ip in [KroghInterpolator, BarycentricInterpolator]:
+        def interpolator_derivs(x, y, axis=0):
+            return ip(x, y, axis).derivatives
+
+        for s1 in SHAPES:
+            for s2 in SHAPES:
+                for axis in range(-len(s2), len(s2)):
+                    check_shape(interpolator_derivs, s1, s2, (6,), axis)
+
+
+def test_deriv_shapes():
+    def krogh_deriv(x, y, axis=0):
+        return KroghInterpolator(x, y, axis).derivative
+
+    def bary_deriv(x, y, axis=0):
+        return BarycentricInterpolator(x, y, axis).derivative
+
+    def pchip_deriv(x, y, axis=0):
+        return pchip(x, y, axis).derivative()
+
+    def pchip_deriv2(x, y, axis=0):
+        return pchip(x, y, axis).derivative(2)
+
+    def pchip_antideriv(x, y, axis=0):
+        return pchip(x, y, axis).antiderivative()
+
+    def pchip_antideriv2(x, y, axis=0):
+        return pchip(x, y, axis).antiderivative(2)
+
+    def pchip_deriv_inplace(x, y, axis=0):
+        class P(PchipInterpolator):
+            def __call__(self, x):
+                return PchipInterpolator.__call__(self, x, 1)
+            pass
+        return P(x, y, axis)
+
+    def akima_deriv(x, y, axis=0):
+        return Akima1DInterpolator(x, y, axis).derivative()
+
+    def akima_antideriv(x, y, axis=0):
+        return Akima1DInterpolator(x, y, axis).antiderivative()
+
+    def cspline_deriv(x, y, axis=0):
+        return CubicSpline(x, y, axis).derivative()
+
+    def cspline_antideriv(x, y, axis=0):
+        return CubicSpline(x, y, axis).antiderivative()
+
+    def bspl_deriv(x, y, axis=0):
+        return make_interp_spline(x, y, axis=axis).derivative()
+
+    def bspl_antideriv(x, y, axis=0):
+        return make_interp_spline(x, y, axis=axis).antiderivative()
+
+    for ip in [krogh_deriv, bary_deriv, pchip_deriv, pchip_deriv2, pchip_deriv_inplace,
+               pchip_antideriv, pchip_antideriv2, akima_deriv, akima_antideriv,
+               cspline_deriv, cspline_antideriv, bspl_deriv, bspl_antideriv]:
+        for s1 in SHAPES:
+            for s2 in SHAPES:
+                for axis in range(-len(s2), len(s2)):
+                    check_shape(ip, s1, s2, (), axis)
+
+
+def test_complex():
+    x = [1, 2, 3, 4]
+    y = [1, 2, 1j, 3]
+
+    for ip in [KroghInterpolator, BarycentricInterpolator, CubicSpline]:
+        p = ip(x, y)
+        assert_allclose(y, p(x))
+
+    dydx = [0, -1j, 2, 3j]
+    p = CubicHermiteSpline(x, y, dydx)
+    assert_allclose(y, p(x))
+    assert_allclose(dydx, p(x, 1))
+
+
+class TestKrogh:
+    def setup_method(self):
+        self.true_poly = np.polynomial.Polynomial([-4, 5, 1, 3, -2])
+        self.test_xs = np.linspace(-1,1,100)
+        self.xs = np.linspace(-1,1,5)
+        self.ys = self.true_poly(self.xs)
+
+    def test_lagrange(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        assert_almost_equal(self.true_poly(self.test_xs),P(self.test_xs))
+
+    def test_scalar(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        assert_almost_equal(self.true_poly(7),P(7))
+        assert_almost_equal(self.true_poly(np.array(7)), P(np.array(7)))
+
+    def test_derivatives(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        D = P.derivatives(self.test_xs)
+        for i in range(D.shape[0]):
+            assert_almost_equal(self.true_poly.deriv(i)(self.test_xs),
+                                D[i])
+
+    def test_low_derivatives(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        D = P.derivatives(self.test_xs,len(self.xs)+2)
+        for i in range(D.shape[0]):
+            assert_almost_equal(self.true_poly.deriv(i)(self.test_xs),
+                                D[i])
+
+    def test_derivative(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        m = 10
+        r = P.derivatives(self.test_xs,m)
+        for i in range(m):
+            assert_almost_equal(P.derivative(self.test_xs,i),r[i])
+
+    def test_high_derivative(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        for i in range(len(self.xs), 2*len(self.xs)):
+            assert_almost_equal(P.derivative(self.test_xs,i),
+                                np.zeros(len(self.test_xs)))
+
+    def test_ndim_derivatives(self):
+        poly1 = self.true_poly
+        poly2 = np.polynomial.Polynomial([-2, 5, 3, -1])
+        poly3 = np.polynomial.Polynomial([12, -3, 4, -5, 6])
+        ys = np.stack((poly1(self.xs), poly2(self.xs), poly3(self.xs)), axis=-1)
+
+        P = KroghInterpolator(self.xs, ys, axis=0)
+        D = P.derivatives(self.test_xs)
+        for i in range(D.shape[0]):
+            assert_allclose(D[i],
+                            np.stack((poly1.deriv(i)(self.test_xs),
+                                      poly2.deriv(i)(self.test_xs),
+                                      poly3.deriv(i)(self.test_xs)),
+                                     axis=-1))
+
+    def test_ndim_derivative(self):
+        poly1 = self.true_poly
+        poly2 = np.polynomial.Polynomial([-2, 5, 3, -1])
+        poly3 = np.polynomial.Polynomial([12, -3, 4, -5, 6])
+        ys = np.stack((poly1(self.xs), poly2(self.xs), poly3(self.xs)), axis=-1)
+
+        P = KroghInterpolator(self.xs, ys, axis=0)
+        for i in range(P.n):
+            assert_allclose(P.derivative(self.test_xs, i),
+                            np.stack((poly1.deriv(i)(self.test_xs),
+                                      poly2.deriv(i)(self.test_xs),
+                                      poly3.deriv(i)(self.test_xs)),
+                                     axis=-1))
+
+    def test_hermite(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        assert_almost_equal(self.true_poly(self.test_xs),P(self.test_xs))
+
+    def test_vector(self):
+        xs = [0, 1, 2]
+        ys = np.array([[0,1],[1,0],[2,1]])
+        P = KroghInterpolator(xs,ys)
+        Pi = [KroghInterpolator(xs,ys[:,i]) for i in range(ys.shape[1])]
+        test_xs = np.linspace(-1,3,100)
+        assert_almost_equal(P(test_xs),
+                            np.asarray([p(test_xs) for p in Pi]).T)
+        assert_almost_equal(P.derivatives(test_xs),
+                np.transpose(np.asarray([p.derivatives(test_xs) for p in Pi]),
+                    (1,2,0)))
+
+    def test_empty(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        assert_array_equal(P([]), [])
+
+    def test_shapes_scalarvalue(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        assert_array_equal(np.shape(P(0)), ())
+        assert_array_equal(np.shape(P(np.array(0))), ())
+        assert_array_equal(np.shape(P([0])), (1,))
+        assert_array_equal(np.shape(P([0,1])), (2,))
+
+    def test_shapes_scalarvalue_derivative(self):
+        P = KroghInterpolator(self.xs,self.ys)
+        n = P.n
+        assert_array_equal(np.shape(P.derivatives(0)), (n,))
+        assert_array_equal(np.shape(P.derivatives(np.array(0))), (n,))
+        assert_array_equal(np.shape(P.derivatives([0])), (n,1))
+        assert_array_equal(np.shape(P.derivatives([0,1])), (n,2))
+
+    def test_shapes_vectorvalue(self):
+        P = KroghInterpolator(self.xs,np.outer(self.ys,np.arange(3)))
+        assert_array_equal(np.shape(P(0)), (3,))
+        assert_array_equal(np.shape(P([0])), (1,3))
+        assert_array_equal(np.shape(P([0,1])), (2,3))
+
+    def test_shapes_1d_vectorvalue(self):
+        P = KroghInterpolator(self.xs,np.outer(self.ys,[1]))
+        assert_array_equal(np.shape(P(0)), (1,))
+        assert_array_equal(np.shape(P([0])), (1,1))
+        assert_array_equal(np.shape(P([0,1])), (2,1))
+
+    def test_shapes_vectorvalue_derivative(self):
+        P = KroghInterpolator(self.xs,np.outer(self.ys,np.arange(3)))
+        n = P.n
+        assert_array_equal(np.shape(P.derivatives(0)), (n,3))
+        assert_array_equal(np.shape(P.derivatives([0])), (n,1,3))
+        assert_array_equal(np.shape(P.derivatives([0,1])), (n,2,3))
+
+    def test_wrapper(self):
+        P = KroghInterpolator(self.xs, self.ys)
+        ki = krogh_interpolate
+        assert_almost_equal(P(self.test_xs), ki(self.xs, self.ys, self.test_xs))
+        assert_almost_equal(P.derivative(self.test_xs, 2),
+                            ki(self.xs, self.ys, self.test_xs, der=2))
+        assert_almost_equal(P.derivatives(self.test_xs, 2),
+                            ki(self.xs, self.ys, self.test_xs, der=[0, 1]))
+
+    def test_int_inputs(self):
+        # Check input args are cast correctly to floats, gh-3669
+        x = [0, 234, 468, 702, 936, 1170, 1404, 2340, 3744, 6084, 8424,
+             13104, 60000]
+        offset_cdf = np.array([-0.95, -0.86114777, -0.8147762, -0.64072425,
+                               -0.48002351, -0.34925329, -0.26503107,
+                               -0.13148093, -0.12988833, -0.12979296,
+                               -0.12973574, -0.08582937, 0.05])
+        f = KroghInterpolator(x, offset_cdf)
+
+        assert_allclose(abs((f(x) - offset_cdf) / f.derivative(x, 1)),
+                        0, atol=1e-10)
+
+    def test_derivatives_complex(self):
+        # regression test for gh-7381: krogh.derivatives(0) fails complex y
+        x, y = np.array([-1, -1, 0, 1, 1]), np.array([1, 1.0j, 0, -1, 1.0j])
+        func = KroghInterpolator(x, y)
+        cmplx = func.derivatives(0)
+
+        cmplx2 = (KroghInterpolator(x, y.real).derivatives(0) +
+                  1j*KroghInterpolator(x, y.imag).derivatives(0))
+        assert_allclose(cmplx, cmplx2, atol=1e-15)
+
+    def test_high_degree_warning(self):
+        with pytest.warns(UserWarning, match="40 degrees provided,"):
+            KroghInterpolator(np.arange(40), np.ones(40))
+
+
+class TestTaylor:
+    def test_exponential(self):
+        degree = 5
+        p = approximate_taylor_polynomial(np.exp, 0, degree, 1, 15)
+        for i in range(degree+1):
+            assert_almost_equal(p(0),1)
+            p = p.deriv()
+        assert_almost_equal(p(0),0)
+
+
+class TestBarycentric:
+    def setup_method(self):
+        self.true_poly = np.polynomial.Polynomial([-4, 5, 1, 3, -2])
+        self.test_xs = np.linspace(-1, 1, 100)
+        self.xs = np.linspace(-1, 1, 5)
+        self.ys = self.true_poly(self.xs)
+
+    def test_lagrange(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        assert_allclose(P(self.test_xs), self.true_poly(self.test_xs))
+
+    def test_scalar(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        assert_allclose(P(7), self.true_poly(7))
+        assert_allclose(P(np.array(7)), self.true_poly(np.array(7)))
+
+    def test_derivatives(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        D = P.derivatives(self.test_xs)
+        for i in range(D.shape[0]):
+            assert_allclose(self.true_poly.deriv(i)(self.test_xs), D[i])
+
+    def test_low_derivatives(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        D = P.derivatives(self.test_xs, len(self.xs)+2)
+        for i in range(D.shape[0]):
+            assert_allclose(self.true_poly.deriv(i)(self.test_xs),
+                            D[i],
+                            atol=1e-12)
+
+    def test_derivative(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        m = 10
+        r = P.derivatives(self.test_xs, m)
+        for i in range(m):
+            assert_allclose(P.derivative(self.test_xs, i), r[i])
+
+    def test_high_derivative(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        for i in range(len(self.xs), 5*len(self.xs)):
+            assert_allclose(P.derivative(self.test_xs, i),
+                            np.zeros(len(self.test_xs)))
+
+    def test_ndim_derivatives(self):
+        poly1 = self.true_poly
+        poly2 = np.polynomial.Polynomial([-2, 5, 3, -1])
+        poly3 = np.polynomial.Polynomial([12, -3, 4, -5, 6])
+        ys = np.stack((poly1(self.xs), poly2(self.xs), poly3(self.xs)), axis=-1)
+
+        P = BarycentricInterpolator(self.xs, ys, axis=0)
+        D = P.derivatives(self.test_xs)
+        for i in range(D.shape[0]):
+            assert_allclose(D[i],
+                            np.stack((poly1.deriv(i)(self.test_xs),
+                                      poly2.deriv(i)(self.test_xs),
+                                      poly3.deriv(i)(self.test_xs)),
+                                     axis=-1),
+                            atol=1e-12)
+
+    def test_ndim_derivative(self):
+        poly1 = self.true_poly
+        poly2 = np.polynomial.Polynomial([-2, 5, 3, -1])
+        poly3 = np.polynomial.Polynomial([12, -3, 4, -5, 6])
+        ys = np.stack((poly1(self.xs), poly2(self.xs), poly3(self.xs)), axis=-1)
+
+        P = BarycentricInterpolator(self.xs, ys, axis=0)
+        for i in range(P.n):
+            assert_allclose(P.derivative(self.test_xs, i),
+                            np.stack((poly1.deriv(i)(self.test_xs),
+                                      poly2.deriv(i)(self.test_xs),
+                                      poly3.deriv(i)(self.test_xs)),
+                                     axis=-1),
+                            atol=1e-12)
+
+    def test_delayed(self):
+        P = BarycentricInterpolator(self.xs)
+        P.set_yi(self.ys)
+        assert_almost_equal(self.true_poly(self.test_xs), P(self.test_xs))
+
+    def test_append(self):
+        P = BarycentricInterpolator(self.xs[:3], self.ys[:3])
+        P.add_xi(self.xs[3:], self.ys[3:])
+        assert_almost_equal(self.true_poly(self.test_xs), P(self.test_xs))
+
+    def test_vector(self):
+        xs = [0, 1, 2]
+        ys = np.array([[0, 1], [1, 0], [2, 1]])
+        BI = BarycentricInterpolator
+        P = BI(xs, ys)
+        Pi = [BI(xs, ys[:, i]) for i in range(ys.shape[1])]
+        test_xs = np.linspace(-1, 3, 100)
+        assert_almost_equal(P(test_xs),
+                            np.asarray([p(test_xs) for p in Pi]).T)
+
+    def test_shapes_scalarvalue(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        assert_array_equal(np.shape(P(0)), ())
+        assert_array_equal(np.shape(P(np.array(0))), ())
+        assert_array_equal(np.shape(P([0])), (1,))
+        assert_array_equal(np.shape(P([0, 1])), (2,))
+
+    def test_shapes_scalarvalue_derivative(self):
+        P = BarycentricInterpolator(self.xs,self.ys)
+        n = P.n
+        assert_array_equal(np.shape(P.derivatives(0)), (n,))
+        assert_array_equal(np.shape(P.derivatives(np.array(0))), (n,))
+        assert_array_equal(np.shape(P.derivatives([0])), (n,1))
+        assert_array_equal(np.shape(P.derivatives([0,1])), (n,2))
+
+    def test_shapes_vectorvalue(self):
+        P = BarycentricInterpolator(self.xs, np.outer(self.ys, np.arange(3)))
+        assert_array_equal(np.shape(P(0)), (3,))
+        assert_array_equal(np.shape(P([0])), (1, 3))
+        assert_array_equal(np.shape(P([0, 1])), (2, 3))
+
+    def test_shapes_1d_vectorvalue(self):
+        P = BarycentricInterpolator(self.xs, np.outer(self.ys, [1]))
+        assert_array_equal(np.shape(P(0)), (1,))
+        assert_array_equal(np.shape(P([0])), (1, 1))
+        assert_array_equal(np.shape(P([0,1])), (2, 1))
+
+    def test_shapes_vectorvalue_derivative(self):
+        P = BarycentricInterpolator(self.xs,np.outer(self.ys,np.arange(3)))
+        n = P.n
+        assert_array_equal(np.shape(P.derivatives(0)), (n,3))
+        assert_array_equal(np.shape(P.derivatives([0])), (n,1,3))
+        assert_array_equal(np.shape(P.derivatives([0,1])), (n,2,3))
+
+    def test_wrapper(self):
+        P = BarycentricInterpolator(self.xs, self.ys)
+        bi = barycentric_interpolate
+        assert_allclose(P(self.test_xs), bi(self.xs, self.ys, self.test_xs))
+        assert_allclose(P.derivative(self.test_xs, 2),
+                            bi(self.xs, self.ys, self.test_xs, der=2))
+        assert_allclose(P.derivatives(self.test_xs, 2),
+                            bi(self.xs, self.ys, self.test_xs, der=[0, 1]))
+
+    def test_int_input(self):
+        x = 1000 * np.arange(1, 11)  # np.prod(x[-1] - x[:-1]) overflows
+        y = np.arange(1, 11)
+        value = barycentric_interpolate(x, y, 1000 * 9.5)
+        assert_almost_equal(value, 9.5)
+
+    def test_large_chebyshev(self):
+        # The weights for Chebyshev points of the second kind have analytically
+        # solvable weights. Naive calculation of barycentric weights will fail
+        # for large N because of numerical underflow and overflow. We test
+        # correctness for large N against analytical Chebyshev weights.
+
+        # Without capacity scaling or permutation, n=800 fails,
+        # With just capacity scaling, n=1097 fails
+        # With both capacity scaling and random permutation, n=30000 succeeds
+        n = 1100
+        j = np.arange(n + 1).astype(np.float64)
+        x = np.cos(j * np.pi / n)
+
+        # See page 506 of Berrut and Trefethen 2004 for this formula
+        w = (-1) ** j
+        w[0] *= 0.5
+        w[-1] *= 0.5
+
+        P = BarycentricInterpolator(x)
+
+        # It's okay to have a constant scaling factor in the weights because it
+        # cancels out in the evaluation of the polynomial.
+        factor = P.wi[0]
+        assert_almost_equal(P.wi / (2 * factor), w)
+
+    def test_warning(self):
+        # Test if the divide-by-zero warning is properly ignored when computing
+        # interpolated values equals to interpolation points
+        P = BarycentricInterpolator([0, 1], [1, 2])
+        with np.errstate(divide='raise'):
+            yi = P(P.xi)
+
+        # Check if the interpolated values match the input values
+        # at the nodes
+        assert_almost_equal(yi, P.yi.ravel())
+
+    def test_repeated_node(self):
+        # check that a repeated node raises a ValueError
+        # (computing the weights requires division by xi[i] - xi[j])
+        xis = np.array([0.1, 0.5, 0.9, 0.5])
+        ys = np.array([1, 2, 3, 4])
+        with pytest.raises(ValueError,
+                           match="Interpolation points xi must be distinct."):
+            BarycentricInterpolator(xis, ys)
+
+
+class TestPCHIP:
+    def _make_random(self, npts=20):
+        np.random.seed(1234)
+        xi = np.sort(np.random.random(npts))
+        yi = np.random.random(npts)
+        return pchip(xi, yi), xi, yi
+
+    def test_overshoot(self):
+        # PCHIP should not overshoot
+        p, xi, yi = self._make_random()
+        for i in range(len(xi)-1):
+            x1, x2 = xi[i], xi[i+1]
+            y1, y2 = yi[i], yi[i+1]
+            if y1 > y2:
+                y1, y2 = y2, y1
+            xp = np.linspace(x1, x2, 10)
+            yp = p(xp)
+            assert_(((y1 <= yp + 1e-15) & (yp <= y2 + 1e-15)).all())
+
+    def test_monotone(self):
+        # PCHIP should preserve monotonicty
+        p, xi, yi = self._make_random()
+        for i in range(len(xi)-1):
+            x1, x2 = xi[i], xi[i+1]
+            y1, y2 = yi[i], yi[i+1]
+            xp = np.linspace(x1, x2, 10)
+            yp = p(xp)
+            assert_(((y2-y1) * (yp[1:] - yp[:1]) > 0).all())
+
+    def test_cast(self):
+        # regression test for integer input data, see gh-3453
+        data = np.array([[0, 4, 12, 27, 47, 60, 79, 87, 99, 100],
+                         [-33, -33, -19, -2, 12, 26, 38, 45, 53, 55]])
+        xx = np.arange(100)
+        curve = pchip(data[0], data[1])(xx)
+
+        data1 = data * 1.0
+        curve1 = pchip(data1[0], data1[1])(xx)
+
+        assert_allclose(curve, curve1, atol=1e-14, rtol=1e-14)
+
+    def test_nag(self):
+        # Example from NAG C implementation,
+        # http://nag.com/numeric/cl/nagdoc_cl25/html/e01/e01bec.html
+        # suggested in gh-5326 as a smoke test for the way the derivatives
+        # are computed (see also gh-3453)
+        dataStr = '''
+          7.99   0.00000E+0
+          8.09   0.27643E-4
+          8.19   0.43750E-1
+          8.70   0.16918E+0
+          9.20   0.46943E+0
+         10.00   0.94374E+0
+         12.00   0.99864E+0
+         15.00   0.99992E+0
+         20.00   0.99999E+0
+        '''
+        data = np.loadtxt(io.StringIO(dataStr))
+        pch = pchip(data[:,0], data[:,1])
+
+        resultStr = '''
+           7.9900       0.0000
+           9.1910       0.4640
+          10.3920       0.9645
+          11.5930       0.9965
+          12.7940       0.9992
+          13.9950       0.9998
+          15.1960       0.9999
+          16.3970       1.0000
+          17.5980       1.0000
+          18.7990       1.0000
+          20.0000       1.0000
+        '''
+        result = np.loadtxt(io.StringIO(resultStr))
+        assert_allclose(result[:,1], pch(result[:,0]), rtol=0., atol=5e-5)
+
+    def test_endslopes(self):
+        # this is a smoke test for gh-3453: PCHIP interpolator should not
+        # set edge slopes to zero if the data do not suggest zero edge derivatives
+        x = np.array([0.0, 0.1, 0.25, 0.35])
+        y1 = np.array([279.35, 0.5e3, 1.0e3, 2.5e3])
+        y2 = np.array([279.35, 2.5e3, 1.50e3, 1.0e3])
+        for pp in (pchip(x, y1), pchip(x, y2)):
+            for t in (x[0], x[-1]):
+                assert_(pp(t, 1) != 0)
+
+    def test_all_zeros(self):
+        x = np.arange(10)
+        y = np.zeros_like(x)
+
+        # this should work and not generate any warnings
+        with warnings.catch_warnings():
+            warnings.filterwarnings('error')
+            pch = pchip(x, y)
+
+        xx = np.linspace(0, 9, 101)
+        assert_equal(pch(xx), 0.)
+
+    def test_two_points(self):
+        # regression test for gh-6222: pchip([0, 1], [0, 1]) fails because
+        # it tries to use a three-point scheme to estimate edge derivatives,
+        # while there are only two points available.
+        # Instead, it should construct a linear interpolator.
+        x = np.linspace(0, 1, 11)
+        p = pchip([0, 1], [0, 2])
+        assert_allclose(p(x), 2*x, atol=1e-15)
+
+    def test_pchip_interpolate(self):
+        assert_array_almost_equal(
+            pchip_interpolate([1,2,3], [4,5,6], [0.5], der=1),
+            [1.])
+
+        assert_array_almost_equal(
+            pchip_interpolate([1,2,3], [4,5,6], [0.5], der=0),
+            [3.5])
+
+        assert_array_almost_equal(
+            pchip_interpolate([1,2,3], [4,5,6], [0.5], der=[0, 1]),
+            [[3.5], [1]])
+
+    def test_roots(self):
+        # regression test for gh-6357: .roots method should work
+        p = pchip([0, 1], [-1, 1])
+        r = p.roots()
+        assert_allclose(r, 0.5)
+
+
+class TestCubicSpline:
+    @staticmethod
+    def check_correctness(S, bc_start='not-a-knot', bc_end='not-a-knot',
+                          tol=1e-14):
+        """Check that spline coefficients satisfy the continuity and boundary
+        conditions."""
+        x = S.x
+        c = S.c
+        dx = np.diff(x)
+        dx = dx.reshape([dx.shape[0]] + [1] * (c.ndim - 2))
+        dxi = dx[:-1]
+
+        # Check C2 continuity.
+        assert_allclose(c[3, 1:], c[0, :-1] * dxi**3 + c[1, :-1] * dxi**2 +
+                        c[2, :-1] * dxi + c[3, :-1], rtol=tol, atol=tol)
+        assert_allclose(c[2, 1:], 3 * c[0, :-1] * dxi**2 +
+                        2 * c[1, :-1] * dxi + c[2, :-1], rtol=tol, atol=tol)
+        assert_allclose(c[1, 1:], 3 * c[0, :-1] * dxi + c[1, :-1],
+                        rtol=tol, atol=tol)
+
+        # Check that we found a parabola, the third derivative is 0.
+        if x.size == 3 and bc_start == 'not-a-knot' and bc_end == 'not-a-knot':
+            assert_allclose(c[0], 0, rtol=tol, atol=tol)
+            return
+
+        # Check periodic boundary conditions.
+        if bc_start == 'periodic':
+            assert_allclose(S(x[0], 0), S(x[-1], 0), rtol=tol, atol=tol)
+            assert_allclose(S(x[0], 1), S(x[-1], 1), rtol=tol, atol=tol)
+            assert_allclose(S(x[0], 2), S(x[-1], 2), rtol=tol, atol=tol)
+            return
+
+        # Check other boundary conditions.
+        if bc_start == 'not-a-knot':
+            if x.size == 2:
+                slope = (S(x[1]) - S(x[0])) / dx[0]
+                assert_allclose(S(x[0], 1), slope, rtol=tol, atol=tol)
+            else:
+                assert_allclose(c[0, 0], c[0, 1], rtol=tol, atol=tol)
+        elif bc_start == 'clamped':
+            assert_allclose(S(x[0], 1), 0, rtol=tol, atol=tol)
+        elif bc_start == 'natural':
+            assert_allclose(S(x[0], 2), 0, rtol=tol, atol=tol)
+        else:
+            order, value = bc_start
+            assert_allclose(S(x[0], order), value, rtol=tol, atol=tol)
+
+        if bc_end == 'not-a-knot':
+            if x.size == 2:
+                slope = (S(x[1]) - S(x[0])) / dx[0]
+                assert_allclose(S(x[1], 1), slope, rtol=tol, atol=tol)
+            else:
+                assert_allclose(c[0, -1], c[0, -2], rtol=tol, atol=tol)
+        elif bc_end == 'clamped':
+            assert_allclose(S(x[-1], 1), 0, rtol=tol, atol=tol)
+        elif bc_end == 'natural':
+            assert_allclose(S(x[-1], 2), 0, rtol=2*tol, atol=2*tol)
+        else:
+            order, value = bc_end
+            assert_allclose(S(x[-1], order), value, rtol=tol, atol=tol)
+
+    def check_all_bc(self, x, y, axis):
+        deriv_shape = list(y.shape)
+        del deriv_shape[axis]
+        first_deriv = np.empty(deriv_shape)
+        first_deriv.fill(2)
+        second_deriv = np.empty(deriv_shape)
+        second_deriv.fill(-1)
+        bc_all = [
+            'not-a-knot',
+            'natural',
+            'clamped',
+            (1, first_deriv),
+            (2, second_deriv)
+        ]
+        for bc in bc_all[:3]:
+            S = CubicSpline(x, y, axis=axis, bc_type=bc)
+            self.check_correctness(S, bc, bc)
+
+        for bc_start in bc_all:
+            for bc_end in bc_all:
+                S = CubicSpline(x, y, axis=axis, bc_type=(bc_start, bc_end))
+                self.check_correctness(S, bc_start, bc_end, tol=2e-14)
+
+    def test_general(self):
+        x = np.array([-1, 0, 0.5, 2, 4, 4.5, 5.5, 9])
+        y = np.array([0, -0.5, 2, 3, 2.5, 1, 1, 0.5])
+        for n in [2, 3, x.size]:
+            self.check_all_bc(x[:n], y[:n], 0)
+
+            Y = np.empty((2, n, 2))
+            Y[0, :, 0] = y[:n]
+            Y[0, :, 1] = y[:n] - 1
+            Y[1, :, 0] = y[:n] + 2
+            Y[1, :, 1] = y[:n] + 3
+            self.check_all_bc(x[:n], Y, 1)
+
+    def test_periodic(self):
+        for n in [2, 3, 5]:
+            x = np.linspace(0, 2 * np.pi, n)
+            y = np.cos(x)
+            S = CubicSpline(x, y, bc_type='periodic')
+            self.check_correctness(S, 'periodic', 'periodic')
+
+            Y = np.empty((2, n, 2))
+            Y[0, :, 0] = y
+            Y[0, :, 1] = y + 2
+            Y[1, :, 0] = y - 1
+            Y[1, :, 1] = y + 5
+            S = CubicSpline(x, Y, axis=1, bc_type='periodic')
+            self.check_correctness(S, 'periodic', 'periodic')
+
+    def test_periodic_eval(self):
+        x = np.linspace(0, 2 * np.pi, 10)
+        y = np.cos(x)
+        S = CubicSpline(x, y, bc_type='periodic')
+        assert_almost_equal(S(1), S(1 + 2 * np.pi), decimal=15)
+
+    def test_second_derivative_continuity_gh_11758(self):
+        # gh-11758: C2 continuity fail
+        x = np.array([0.9, 1.3, 1.9, 2.1, 2.6, 3.0, 3.9, 4.4, 4.7, 5.0, 6.0,
+                      7.0, 8.0, 9.2, 10.5, 11.3, 11.6, 12.0, 12.6, 13.0, 13.3])
+        y = np.array([1.3, 1.5, 1.85, 2.1, 2.6, 2.7, 2.4, 2.15, 2.05, 2.1,
+                      2.25, 2.3, 2.25, 1.95, 1.4, 0.9, 0.7, 0.6, 0.5, 0.4, 1.3])
+        S = CubicSpline(x, y, bc_type='periodic', extrapolate='periodic')
+        self.check_correctness(S, 'periodic', 'periodic')
+
+    def test_three_points(self):
+        # gh-11758: Fails computing a_m2_m1
+        # In this case, s (first derivatives) could be found manually by solving
+        # system of 2 linear equations. Due to solution of this system,
+        # s[i] = (h1m2 + h2m1) / (h1 + h2), where h1 = x[1] - x[0], h2 = x[2] - x[1],
+        # m1 = (y[1] - y[0]) / h1, m2 = (y[2] - y[1]) / h2
+        x = np.array([1.0, 2.75, 3.0])
+        y = np.array([1.0, 15.0, 1.0])
+        S = CubicSpline(x, y, bc_type='periodic')
+        self.check_correctness(S, 'periodic', 'periodic')
+        assert_allclose(S.derivative(1)(x), np.array([-48.0, -48.0, -48.0]))
+
+    def test_periodic_three_points_multidim(self):
+        # make sure one multidimensional interpolator does the same as multiple
+        # one-dimensional interpolators
+        x = np.array([0.0, 1.0, 3.0])
+        y = np.array([[0.0, 1.0], [1.0, 0.0], [0.0, 1.0]])
+        S = CubicSpline(x, y, bc_type="periodic")
+        self.check_correctness(S, 'periodic', 'periodic')
+        S0 = CubicSpline(x, y[:, 0], bc_type="periodic")
+        S1 = CubicSpline(x, y[:, 1], bc_type="periodic")
+        q = np.linspace(0, 2, 5)
+        assert_allclose(S(q)[:, 0], S0(q))
+        assert_allclose(S(q)[:, 1], S1(q))
+
+    def test_dtypes(self):
+        x = np.array([0, 1, 2, 3], dtype=int)
+        y = np.array([-5, 2, 3, 1], dtype=int)
+        S = CubicSpline(x, y)
+        self.check_correctness(S)
+
+        y = np.array([-1+1j, 0.0, 1-1j, 0.5-1.5j])
+        S = CubicSpline(x, y)
+        self.check_correctness(S)
+
+        S = CubicSpline(x, x ** 3, bc_type=("natural", (1, 2j)))
+        self.check_correctness(S, "natural", (1, 2j))
+
+        y = np.array([-5, 2, 3, 1])
+        S = CubicSpline(x, y, bc_type=[(1, 2 + 0.5j), (2, 0.5 - 1j)])
+        self.check_correctness(S, (1, 2 + 0.5j), (2, 0.5 - 1j))
+
+    def test_small_dx(self):
+        rng = np.random.RandomState(0)
+        x = np.sort(rng.uniform(size=100))
+        y = 1e4 + rng.uniform(size=100)
+        S = CubicSpline(x, y)
+        self.check_correctness(S, tol=1e-13)
+
+    def test_incorrect_inputs(self):
+        x = np.array([1, 2, 3, 4])
+        y = np.array([1, 2, 3, 4])
+        xc = np.array([1 + 1j, 2, 3, 4])
+        xn = np.array([np.nan, 2, 3, 4])
+        xo = np.array([2, 1, 3, 4])
+        yn = np.array([np.nan, 2, 3, 4])
+        y3 = [1, 2, 3]
+        x1 = [1]
+        y1 = [1]
+
+        assert_raises(ValueError, CubicSpline, xc, y)
+        assert_raises(ValueError, CubicSpline, xn, y)
+        assert_raises(ValueError, CubicSpline, x, yn)
+        assert_raises(ValueError, CubicSpline, xo, y)
+        assert_raises(ValueError, CubicSpline, x, y3)
+        assert_raises(ValueError, CubicSpline, x[:, np.newaxis], y)
+        assert_raises(ValueError, CubicSpline, x1, y1)
+
+        wrong_bc = [('periodic', 'clamped'),
+                    ((2, 0), (3, 10)),
+                    ((1, 0), ),
+                    (0., 0.),
+                    'not-a-typo']
+
+        for bc_type in wrong_bc:
+            assert_raises(ValueError, CubicSpline, x, y, 0, bc_type, True)
+
+        # Shapes mismatch when giving arbitrary derivative values:
+        Y = np.c_[y, y]
+        bc1 = ('clamped', (1, 0))
+        bc2 = ('clamped', (1, [0, 0, 0]))
+        bc3 = ('clamped', (1, [[0, 0]]))
+        assert_raises(ValueError, CubicSpline, x, Y, 0, bc1, True)
+        assert_raises(ValueError, CubicSpline, x, Y, 0, bc2, True)
+        assert_raises(ValueError, CubicSpline, x, Y, 0, bc3, True)
+
+        # periodic condition, y[-1] must be equal to y[0]:
+        assert_raises(ValueError, CubicSpline, x, y, 0, 'periodic', True)
+
+
+def test_CubicHermiteSpline_correctness():
+    x = [0, 2, 7]
+    y = [-1, 2, 3]
+    dydx = [0, 3, 7]
+    s = CubicHermiteSpline(x, y, dydx)
+    assert_allclose(s(x), y, rtol=1e-15)
+    assert_allclose(s(x, 1), dydx, rtol=1e-15)
+
+
+def test_CubicHermiteSpline_error_handling():
+    x = [1, 2, 3]
+    y = [0, 3, 5]
+    dydx = [1, -1, 2, 3]
+    assert_raises(ValueError, CubicHermiteSpline, x, y, dydx)
+
+    dydx_with_nan = [1, 0, np.nan]
+    assert_raises(ValueError, CubicHermiteSpline, x, y, dydx_with_nan)
+
+
+def test_roots_extrapolate_gh_11185():
+    x = np.array([0.001, 0.002])
+    y = np.array([1.66066935e-06, 1.10410807e-06])
+    dy = np.array([-1.60061854, -1.600619])
+    p = CubicHermiteSpline(x, y, dy)
+
+    # roots(extrapolate=True) for a polynomial with a single interval
+    # should return all three real roots
+    r = p.roots(extrapolate=True)
+    assert_equal(p.c.shape[1], 1)
+    assert_equal(r.size, 3)
+
+
+class TestZeroSizeArrays:
+    # regression tests for gh-17241 : CubicSpline et al must not segfault
+    # when y.size == 0
+    # The two methods below are _almost_ the same, but not quite:
+    # one is for objects which have the `bc_type` argument (CubicSpline)
+    # and the other one is for those which do not (Pchip, Akima1D)
+
+    @pytest.mark.parametrize('y', [np.zeros((10, 0, 5)),
+                                   np.zeros((10, 5, 0))])
+    @pytest.mark.parametrize('bc_type',
+                             ['not-a-knot', 'periodic', 'natural', 'clamped'])
+    @pytest.mark.parametrize('axis', [0, 1, 2])
+    @pytest.mark.parametrize('cls', [make_interp_spline, CubicSpline])
+    def test_zero_size(self, cls, y, bc_type, axis):
+        x = np.arange(10)
+        xval = np.arange(3)
+
+        obj = cls(x, y, bc_type=bc_type)
+        assert obj(xval).size == 0
+        assert obj(xval).shape == xval.shape + y.shape[1:]
+
+        # Also check with an explicit non-default axis
+        yt = np.moveaxis(y, 0, axis)  # (10, 0, 5) --> (0, 10, 5) if axis=1 etc
+
+        obj = cls(x, yt, bc_type=bc_type, axis=axis)
+        sh = yt.shape[:axis] + (xval.size, ) + yt.shape[axis+1:]
+        assert obj(xval).size == 0
+        assert obj(xval).shape == sh
+
+    @pytest.mark.parametrize('y', [np.zeros((10, 0, 5)),
+                                   np.zeros((10, 5, 0))])
+    @pytest.mark.parametrize('axis', [0, 1, 2])
+    @pytest.mark.parametrize('cls', [PchipInterpolator, Akima1DInterpolator])
+    def test_zero_size_2(self, cls, y, axis):
+        x = np.arange(10)
+        xval = np.arange(3)
+
+        obj = cls(x, y)
+        assert obj(xval).size == 0
+        assert obj(xval).shape == xval.shape + y.shape[1:]
+
+        # Also check with an explicit non-default axis
+        yt = np.moveaxis(y, 0, axis)  # (10, 0, 5) --> (0, 10, 5) if axis=1 etc
+
+        obj = cls(x, yt, axis=axis)
+        sh = yt.shape[:axis] + (xval.size, ) + yt.shape[axis+1:]
+        assert obj(xval).size == 0
+        assert obj(xval).shape == sh

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_rbf.py

@@ -0,0 +1,222 @@
+# Created by John Travers, Robert Hetland, 2007
+""" Test functions for rbf module """
+
+import numpy as np
+from numpy.testing import (assert_, assert_array_almost_equal,
+                           assert_almost_equal)
+from numpy import linspace, sin, cos, random, exp, allclose
+from scipy.interpolate._rbf import Rbf
+
+FUNCTIONS = ('multiquadric', 'inverse multiquadric', 'gaussian',
+             'cubic', 'quintic', 'thin-plate', 'linear')
+
+
+def check_rbf1d_interpolation(function):
+    # Check that the Rbf function interpolates through the nodes (1D)
+    x = linspace(0,10,9)
+    y = sin(x)
+    rbf = Rbf(x, y, function=function)
+    yi = rbf(x)
+    assert_array_almost_equal(y, yi)
+    assert_almost_equal(rbf(float(x[0])), y[0])
+
+
+def check_rbf2d_interpolation(function):
+    # Check that the Rbf function interpolates through the nodes (2D).
+    x = random.rand(50,1)*4-2
+    y = random.rand(50,1)*4-2
+    z = x*exp(-x**2-1j*y**2)
+    rbf = Rbf(x, y, z, epsilon=2, function=function)
+    zi = rbf(x, y)
+    zi.shape = x.shape
+    assert_array_almost_equal(z, zi)
+
+
+def check_rbf3d_interpolation(function):
+    # Check that the Rbf function interpolates through the nodes (3D).
+    x = random.rand(50, 1)*4 - 2
+    y = random.rand(50, 1)*4 - 2
+    z = random.rand(50, 1)*4 - 2
+    d = x*exp(-x**2 - y**2)
+    rbf = Rbf(x, y, z, d, epsilon=2, function=function)
+    di = rbf(x, y, z)
+    di.shape = x.shape
+    assert_array_almost_equal(di, d)
+
+
+def test_rbf_interpolation():
+    for function in FUNCTIONS:
+        check_rbf1d_interpolation(function)
+        check_rbf2d_interpolation(function)
+        check_rbf3d_interpolation(function)
+
+
+def check_2drbf1d_interpolation(function):
+    # Check that the 2-D Rbf function interpolates through the nodes (1D)
+    x = linspace(0, 10, 9)
+    y0 = sin(x)
+    y1 = cos(x)
+    y = np.vstack([y0, y1]).T
+    rbf = Rbf(x, y, function=function, mode='N-D')
+    yi = rbf(x)
+    assert_array_almost_equal(y, yi)
+    assert_almost_equal(rbf(float(x[0])), y[0])
+
+
+def check_2drbf2d_interpolation(function):
+    # Check that the 2-D Rbf function interpolates through the nodes (2D).
+    x = random.rand(50, ) * 4 - 2
+    y = random.rand(50, ) * 4 - 2
+    z0 = x * exp(-x ** 2 - 1j * y ** 2)
+    z1 = y * exp(-y ** 2 - 1j * x ** 2)
+    z = np.vstack([z0, z1]).T
+    rbf = Rbf(x, y, z, epsilon=2, function=function, mode='N-D')
+    zi = rbf(x, y)
+    zi.shape = z.shape
+    assert_array_almost_equal(z, zi)
+
+
+def check_2drbf3d_interpolation(function):
+    # Check that the 2-D Rbf function interpolates through the nodes (3D).
+    x = random.rand(50, ) * 4 - 2
+    y = random.rand(50, ) * 4 - 2
+    z = random.rand(50, ) * 4 - 2
+    d0 = x * exp(-x ** 2 - y ** 2)
+    d1 = y * exp(-y ** 2 - x ** 2)
+    d = np.vstack([d0, d1]).T
+    rbf = Rbf(x, y, z, d, epsilon=2, function=function, mode='N-D')
+    di = rbf(x, y, z)
+    di.shape = d.shape
+    assert_array_almost_equal(di, d)
+
+
+def test_2drbf_interpolation():
+    for function in FUNCTIONS:
+        check_2drbf1d_interpolation(function)
+        check_2drbf2d_interpolation(function)
+        check_2drbf3d_interpolation(function)
+
+
+def check_rbf1d_regularity(function, atol):
+    # Check that the Rbf function approximates a smooth function well away
+    # from the nodes.
+    x = linspace(0, 10, 9)
+    y = sin(x)
+    rbf = Rbf(x, y, function=function)
+    xi = linspace(0, 10, 100)
+    yi = rbf(xi)
+    msg = "abs-diff: %f" % abs(yi - sin(xi)).max()
+    assert_(allclose(yi, sin(xi), atol=atol), msg)
+
+
+def test_rbf_regularity():
+    tolerances = {
+        'multiquadric': 0.1,
+        'inverse multiquadric': 0.15,
+        'gaussian': 0.15,
+        'cubic': 0.15,
+        'quintic': 0.1,
+        'thin-plate': 0.1,
+        'linear': 0.2
+    }
+    for function in FUNCTIONS:
+        check_rbf1d_regularity(function, tolerances.get(function, 1e-2))
+
+
+def check_2drbf1d_regularity(function, atol):
+    # Check that the 2-D Rbf function approximates a smooth function well away
+    # from the nodes.
+    x = linspace(0, 10, 9)
+    y0 = sin(x)
+    y1 = cos(x)
+    y = np.vstack([y0, y1]).T
+    rbf = Rbf(x, y, function=function, mode='N-D')
+    xi = linspace(0, 10, 100)
+    yi = rbf(xi)
+    msg = "abs-diff: %f" % abs(yi - np.vstack([sin(xi), cos(xi)]).T).max()
+    assert_(allclose(yi, np.vstack([sin(xi), cos(xi)]).T, atol=atol), msg)
+
+
+def test_2drbf_regularity():
+    tolerances = {
+        'multiquadric': 0.1,
+        'inverse multiquadric': 0.15,
+        'gaussian': 0.15,
+        'cubic': 0.15,
+        'quintic': 0.1,
+        'thin-plate': 0.15,
+        'linear': 0.2
+    }
+    for function in FUNCTIONS:
+        check_2drbf1d_regularity(function, tolerances.get(function, 1e-2))
+
+
+def check_rbf1d_stability(function):
+    # Check that the Rbf function with default epsilon is not subject
+    # to overshoot. Regression for issue #4523.
+    #
+    # Generate some data (fixed random seed hence deterministic)
+    np.random.seed(1234)
+    x = np.linspace(0, 10, 50)
+    z = x + 4.0 * np.random.randn(len(x))
+
+    rbf = Rbf(x, z, function=function)
+    xi = np.linspace(0, 10, 1000)
+    yi = rbf(xi)
+
+    # subtract the linear trend and make sure there no spikes
+    assert_(np.abs(yi-xi).max() / np.abs(z-x).max() < 1.1)
+
+def test_rbf_stability():
+    for function in FUNCTIONS:
+        check_rbf1d_stability(function)
+
+
+def test_default_construction():
+    # Check that the Rbf class can be constructed with the default
+    # multiquadric basis function. Regression test for ticket #1228.
+    x = linspace(0,10,9)
+    y = sin(x)
+    rbf = Rbf(x, y)
+    yi = rbf(x)
+    assert_array_almost_equal(y, yi)
+
+
+def test_function_is_callable():
+    # Check that the Rbf class can be constructed with function=callable.
+    x = linspace(0,10,9)
+    y = sin(x)
+    def linfunc(x):
+        return x
+    rbf = Rbf(x, y, function=linfunc)
+    yi = rbf(x)
+    assert_array_almost_equal(y, yi)
+
+
+def test_two_arg_function_is_callable():
+    # Check that the Rbf class can be constructed with a two argument
+    # function=callable.
+    def _func(self, r):
+        return self.epsilon + r
+
+    x = linspace(0,10,9)
+    y = sin(x)
+    rbf = Rbf(x, y, function=_func)
+    yi = rbf(x)
+    assert_array_almost_equal(y, yi)
+
+
+def test_rbf_epsilon_none():
+    x = linspace(0, 10, 9)
+    y = sin(x)
+    Rbf(x, y, epsilon=None)
+
+
+def test_rbf_epsilon_none_collinear():
+    # Check that collinear points in one dimension doesn't cause an error
+    # due to epsilon = 0
+    x = [1, 2, 3]
+    y = [4, 4, 4]
+    z = [5, 6, 7]
+    rbf = Rbf(x, y, z, epsilon=None)
+    assert_(rbf.epsilon > 0)

venv/lib/python3.12/site-packages/scipy/interpolate/tests/test_rbfinterp.py

@@ -0,0 +1,516 @@
+import pickle
+import pytest
+import numpy as np
+from numpy.linalg import LinAlgError
+from numpy.testing import assert_allclose
+from scipy.stats.qmc import Halton
+from scipy.spatial import cKDTree
+from scipy.interpolate._rbfinterp import (
+    _AVAILABLE, _SCALE_INVARIANT, _NAME_TO_MIN_DEGREE, _monomial_powers,
+    RBFInterpolator
+    )
+from scipy.interpolate import _rbfinterp_pythran
+
+
+def _vandermonde(x, degree):
+    # Returns a matrix of monomials that span polynomials with the specified
+    # degree evaluated at x.
+    powers = _monomial_powers(x.shape[1], degree)
+    return _rbfinterp_pythran._polynomial_matrix(x, powers)
+
+
+def _1d_test_function(x):
+    # Test function used in Wahba's "Spline Models for Observational Data".
+    # domain ~= (0, 3), range ~= (-1.0, 0.2)
+    x = x[:, 0]
+    y = 4.26*(np.exp(-x) - 4*np.exp(-2*x) + 3*np.exp(-3*x))
+    return y
+
+
+def _2d_test_function(x):
+    # Franke's test function.
+    # domain ~= (0, 1) X (0, 1), range ~= (0.0, 1.2)
+    x1, x2 = x[:, 0], x[:, 1]
+    term1 = 0.75 * np.exp(-(9*x1-2)**2/4 - (9*x2-2)**2/4)
+    term2 = 0.75 * np.exp(-(9*x1+1)**2/49 - (9*x2+1)/10)
+    term3 = 0.5 * np.exp(-(9*x1-7)**2/4 - (9*x2-3)**2/4)
+    term4 = -0.2 * np.exp(-(9*x1-4)**2 - (9*x2-7)**2)
+    y = term1 + term2 + term3 + term4
+    return y
+
+
+def _is_conditionally_positive_definite(kernel, m):
+    # Tests whether the kernel is conditionally positive definite of order m.
+    # See chapter 7 of Fasshauer's "Meshfree Approximation Methods with
+    # MATLAB".
+    nx = 10
+    ntests = 100
+    for ndim in [1, 2, 3, 4, 5]:
+        # Generate sample points with a Halton sequence to avoid samples that
+        # are too close to each other, which can make the matrix singular.
+        seq = Halton(ndim, scramble=False, seed=np.random.RandomState())
+        for _ in range(ntests):
+            x = 2*seq.random(nx) - 1
+            A = _rbfinterp_pythran._kernel_matrix(x, kernel)
+            P = _vandermonde(x, m - 1)
+            Q, R = np.linalg.qr(P, mode='complete')
+            # Q2 forms a basis spanning the space where P.T.dot(x) = 0. Project
+            # A onto this space, and then see if it is positive definite using
+            # the Cholesky decomposition. If not, then the kernel is not c.p.d.
+            # of order m.
+            Q2 = Q[:, P.shape[1]:]
+            B = Q2.T.dot(A).dot(Q2)
+            try:
+                np.linalg.cholesky(B)
+            except np.linalg.LinAlgError:
+                return False
+
+    return True
+
+
+# Sorting the parametrize arguments is necessary to avoid a parallelization
+# issue described here: https://github.com/pytest-dev/pytest-xdist/issues/432.
+@pytest.mark.parametrize('kernel', sorted(_AVAILABLE))
+def test_conditionally_positive_definite(kernel):
+    # Test if each kernel in _AVAILABLE is conditionally positive definite of
+    # order m, where m comes from _NAME_TO_MIN_DEGREE. This is a necessary
+    # condition for the smoothed RBF interpolant to be well-posed in general.
+    m = _NAME_TO_MIN_DEGREE.get(kernel, -1) + 1
+    assert _is_conditionally_positive_definite(kernel, m)
+
+
+class _TestRBFInterpolator:
+    @pytest.mark.parametrize('kernel', sorted(_SCALE_INVARIANT))
+    def test_scale_invariance_1d(self, kernel):
+        # Verify that the functions in _SCALE_INVARIANT are insensitive to the
+        # shape parameter (when smoothing == 0) in 1d.
+        seq = Halton(1, scramble=False, seed=np.random.RandomState())
+        x = 3*seq.random(50)
+        y = _1d_test_function(x)
+        xitp = 3*seq.random(50)
+        yitp1 = self.build(x, y, epsilon=1.0, kernel=kernel)(xitp)
+        yitp2 = self.build(x, y, epsilon=2.0, kernel=kernel)(xitp)
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    @pytest.mark.parametrize('kernel', sorted(_SCALE_INVARIANT))
+    def test_scale_invariance_2d(self, kernel):
+        # Verify that the functions in _SCALE_INVARIANT are insensitive to the
+        # shape parameter (when smoothing == 0) in 2d.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+        x = seq.random(100)
+        y = _2d_test_function(x)
+        xitp = seq.random(100)
+        yitp1 = self.build(x, y, epsilon=1.0, kernel=kernel)(xitp)
+        yitp2 = self.build(x, y, epsilon=2.0, kernel=kernel)(xitp)
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    @pytest.mark.parametrize('kernel', sorted(_AVAILABLE))
+    def test_extreme_domains(self, kernel):
+        # Make sure the interpolant remains numerically stable for very
+        # large/small domains.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+        scale = 1e50
+        shift = 1e55
+
+        x = seq.random(100)
+        y = _2d_test_function(x)
+        xitp = seq.random(100)
+
+        if kernel in _SCALE_INVARIANT:
+            yitp1 = self.build(x, y, kernel=kernel)(xitp)
+            yitp2 = self.build(
+                x*scale + shift, y,
+                kernel=kernel
+                )(xitp*scale + shift)
+        else:
+            yitp1 = self.build(x, y, epsilon=5.0, kernel=kernel)(xitp)
+            yitp2 = self.build(
+                x*scale + shift, y,
+                epsilon=5.0/scale,
+                kernel=kernel
+                )(xitp*scale + shift)
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    def test_polynomial_reproduction(self):
+        # If the observed data comes from a polynomial, then the interpolant
+        # should be able to reproduce the polynomial exactly, provided that
+        # `degree` is sufficiently high.
+        rng = np.random.RandomState(0)
+        seq = Halton(2, scramble=False, seed=rng)
+        degree = 3
+
+        x = seq.random(50)
+        xitp = seq.random(50)
+
+        P = _vandermonde(x, degree)
+        Pitp = _vandermonde(xitp, degree)
+
+        poly_coeffs = rng.normal(0.0, 1.0, P.shape[1])
+
+        y = P.dot(poly_coeffs)
+        yitp1 = Pitp.dot(poly_coeffs)
+        yitp2 = self.build(x, y, degree=degree)(xitp)
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    @pytest.mark.slow
+    def test_chunking(self, monkeypatch):
+        # If the observed data comes from a polynomial, then the interpolant
+        # should be able to reproduce the polynomial exactly, provided that
+        # `degree` is sufficiently high.
+        rng = np.random.RandomState(0)
+        seq = Halton(2, scramble=False, seed=rng)
+        degree = 3
+
+        largeN = 1000 + 33
+        # this is large to check that chunking of the RBFInterpolator is tested
+        x = seq.random(50)
+        xitp = seq.random(largeN)
+
+        P = _vandermonde(x, degree)
+        Pitp = _vandermonde(xitp, degree)
+
+        poly_coeffs = rng.normal(0.0, 1.0, P.shape[1])
+
+        y = P.dot(poly_coeffs)
+        yitp1 = Pitp.dot(poly_coeffs)
+        interp = self.build(x, y, degree=degree)
+        ce_real = interp._chunk_evaluator
+
+        def _chunk_evaluator(*args, **kwargs):
+            kwargs.update(memory_budget=100)
+            return ce_real(*args, **kwargs)
+
+        monkeypatch.setattr(interp, '_chunk_evaluator', _chunk_evaluator)
+        yitp2 = interp(xitp)
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    def test_vector_data(self):
+        # Make sure interpolating a vector field is the same as interpolating
+        # each component separately.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+
+        x = seq.random(100)
+        xitp = seq.random(100)
+
+        y = np.array([_2d_test_function(x),
+                      _2d_test_function(x[:, ::-1])]).T
+
+        yitp1 = self.build(x, y)(xitp)
+        yitp2 = self.build(x, y[:, 0])(xitp)
+        yitp3 = self.build(x, y[:, 1])(xitp)
+
+        assert_allclose(yitp1[:, 0], yitp2)
+        assert_allclose(yitp1[:, 1], yitp3)
+
+    def test_complex_data(self):
+        # Interpolating complex input should be the same as interpolating the
+        # real and complex components.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+
+        x = seq.random(100)
+        xitp = seq.random(100)
+
+        y = _2d_test_function(x) + 1j*_2d_test_function(x[:, ::-1])
+
+        yitp1 = self.build(x, y)(xitp)
+        yitp2 = self.build(x, y.real)(xitp)
+        yitp3 = self.build(x, y.imag)(xitp)
+
+        assert_allclose(yitp1.real, yitp2)
+        assert_allclose(yitp1.imag, yitp3)
+
+    @pytest.mark.parametrize('kernel', sorted(_AVAILABLE))
+    def test_interpolation_misfit_1d(self, kernel):
+        # Make sure that each kernel, with its default `degree` and an
+        # appropriate `epsilon`, does a good job at interpolation in 1d.
+        seq = Halton(1, scramble=False, seed=np.random.RandomState())
+
+        x = 3*seq.random(50)
+        xitp = 3*seq.random(50)
+
+        y = _1d_test_function(x)
+        ytrue = _1d_test_function(xitp)
+        yitp = self.build(x, y, epsilon=5.0, kernel=kernel)(xitp)
+
+        mse = np.mean((yitp - ytrue)**2)
+        assert mse < 1.0e-4
+
+    @pytest.mark.parametrize('kernel', sorted(_AVAILABLE))
+    def test_interpolation_misfit_2d(self, kernel):
+        # Make sure that each kernel, with its default `degree` and an
+        # appropriate `epsilon`, does a good job at interpolation in 2d.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+
+        x = seq.random(100)
+        xitp = seq.random(100)
+
+        y = _2d_test_function(x)
+        ytrue = _2d_test_function(xitp)
+        yitp = self.build(x, y, epsilon=5.0, kernel=kernel)(xitp)
+
+        mse = np.mean((yitp - ytrue)**2)
+        assert mse < 2.0e-4
+
+    @pytest.mark.parametrize('kernel', sorted(_AVAILABLE))
+    def test_smoothing_misfit(self, kernel):
+        # Make sure we can find a smoothing parameter for each kernel that
+        # removes a sufficient amount of noise.
+        rng = np.random.RandomState(0)
+        seq = Halton(1, scramble=False, seed=rng)
+
+        noise = 0.2
+        rmse_tol = 0.1
+        smoothing_range = 10**np.linspace(-4, 1, 20)
+
+        x = 3*seq.random(100)
+        y = _1d_test_function(x) + rng.normal(0.0, noise, (100,))
+        ytrue = _1d_test_function(x)
+        rmse_within_tol = False
+        for smoothing in smoothing_range:
+            ysmooth = self.build(
+                x, y,
+                epsilon=1.0,
+                smoothing=smoothing,
+                kernel=kernel)(x)
+            rmse = np.sqrt(np.mean((ysmooth - ytrue)**2))
+            if rmse < rmse_tol:
+                rmse_within_tol = True
+                break
+
+        assert rmse_within_tol
+
+    def test_array_smoothing(self):
+        # Test using an array for `smoothing` to give less weight to a known
+        # outlier.
+        rng = np.random.RandomState(0)
+        seq = Halton(1, scramble=False, seed=rng)
+        degree = 2
+
+        x = seq.random(50)
+        P = _vandermonde(x, degree)
+        poly_coeffs = rng.normal(0.0, 1.0, P.shape[1])
+        y = P.dot(poly_coeffs)
+        y_with_outlier = np.copy(y)
+        y_with_outlier[10] += 1.0
+        smoothing = np.zeros((50,))
+        smoothing[10] = 1000.0
+        yitp = self.build(x, y_with_outlier, smoothing=smoothing)(x)
+        # Should be able to reproduce the uncorrupted data almost exactly.
+        assert_allclose(yitp, y, atol=1e-4)
+
+    def test_inconsistent_x_dimensions_error(self):
+        # ValueError should be raised if the observation points and evaluation
+        # points have a different number of dimensions.
+        y = Halton(2, scramble=False, seed=np.random.RandomState()).random(10)
+        d = _2d_test_function(y)
+        x = Halton(1, scramble=False, seed=np.random.RandomState()).random(10)
+        match = 'Expected the second axis of `x`'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d)(x)
+
+    def test_inconsistent_d_length_error(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(1)
+        match = 'Expected the first axis of `d`'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d)
+
+    def test_y_not_2d_error(self):
+        y = np.linspace(0, 1, 5)
+        d = np.zeros(5)
+        match = '`y` must be a 2-dimensional array.'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d)
+
+    def test_inconsistent_smoothing_length_error(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(5)
+        smoothing = np.ones(1)
+        match = 'Expected `smoothing` to be'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d, smoothing=smoothing)
+
+    def test_invalid_kernel_name_error(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(5)
+        match = '`kernel` must be one of'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d, kernel='test')
+
+    def test_epsilon_not_specified_error(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(5)
+        for kernel in _AVAILABLE:
+            if kernel in _SCALE_INVARIANT:
+                continue
+
+            match = '`epsilon` must be specified'
+            with pytest.raises(ValueError, match=match):
+                self.build(y, d, kernel=kernel)
+
+    def test_x_not_2d_error(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        x = np.linspace(0, 1, 5)
+        d = np.zeros(5)
+        match = '`x` must be a 2-dimensional array.'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d)(x)
+
+    def test_not_enough_observations_error(self):
+        y = np.linspace(0, 1, 1)[:, None]
+        d = np.zeros(1)
+        match = 'At least 2 data points are required'
+        with pytest.raises(ValueError, match=match):
+            self.build(y, d, kernel='thin_plate_spline')
+
+    def test_degree_warning(self):
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(5)
+        for kernel, deg in _NAME_TO_MIN_DEGREE.items():
+            # Only test for kernels that its minimum degree is not 0.
+            if deg >= 1:
+                match = f'`degree` should not be below {deg}'
+                with pytest.warns(Warning, match=match):
+                    self.build(y, d, epsilon=1.0, kernel=kernel, degree=deg-1)
+
+    def test_minus_one_degree(self):
+        # Make sure a degree of -1 is accepted without any warning.
+        y = np.linspace(0, 1, 5)[:, None]
+        d = np.zeros(5)
+        for kernel, _ in _NAME_TO_MIN_DEGREE.items():
+            self.build(y, d, epsilon=1.0, kernel=kernel, degree=-1)
+
+    def test_rank_error(self):
+        # An error should be raised when `kernel` is "thin_plate_spline" and
+        # observations are 2-D and collinear.
+        y = np.array([[2.0, 0.0], [1.0, 0.0], [0.0, 0.0]])
+        d = np.array([0.0, 0.0, 0.0])
+        match = 'does not have full column rank'
+        with pytest.raises(LinAlgError, match=match):
+            self.build(y, d, kernel='thin_plate_spline')(y)
+
+    def test_single_point(self):
+        # Make sure interpolation still works with only one point (in 1, 2, and
+        # 3 dimensions).
+        for dim in [1, 2, 3]:
+            y = np.zeros((1, dim))
+            d = np.ones((1,))
+            f = self.build(y, d, kernel='linear')(y)
+            assert_allclose(d, f)
+
+    def test_pickleable(self):
+        # Make sure we can pickle and unpickle the interpolant without any
+        # changes in the behavior.
+        seq = Halton(1, scramble=False, seed=np.random.RandomState(2305982309))
+
+        x = 3*seq.random(50)
+        xitp = 3*seq.random(50)
+
+        y = _1d_test_function(x)
+
+        interp = self.build(x, y)
+
+        yitp1 = interp(xitp)
+        yitp2 = pickle.loads(pickle.dumps(interp))(xitp)
+
+        assert_allclose(yitp1, yitp2, atol=1e-16)
+
+
+class TestRBFInterpolatorNeighborsNone(_TestRBFInterpolator):
+    def build(self, *args, **kwargs):
+        return RBFInterpolator(*args, **kwargs)
+
+    def test_smoothing_limit_1d(self):
+        # For large smoothing parameters, the interpolant should approach a
+        # least squares fit of a polynomial with the specified degree.
+        seq = Halton(1, scramble=False, seed=np.random.RandomState())
+
+        degree = 3
+        smoothing = 1e8
+
+        x = 3*seq.random(50)
+        xitp = 3*seq.random(50)
+
+        y = _1d_test_function(x)
+
+        yitp1 = self.build(
+            x, y,
+            degree=degree,
+            smoothing=smoothing
+            )(xitp)
+
+        P = _vandermonde(x, degree)
+        Pitp = _vandermonde(xitp, degree)
+        yitp2 = Pitp.dot(np.linalg.lstsq(P, y, rcond=None)[0])
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+    def test_smoothing_limit_2d(self):
+        # For large smoothing parameters, the interpolant should approach a
+        # least squares fit of a polynomial with the specified degree.
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+
+        degree = 3
+        smoothing = 1e8
+
+        x = seq.random(100)
+        xitp = seq.random(100)
+
+        y = _2d_test_function(x)
+
+        yitp1 = self.build(
+            x, y,
+            degree=degree,
+            smoothing=smoothing
+            )(xitp)
+
+        P = _vandermonde(x, degree)
+        Pitp = _vandermonde(xitp, degree)
+        yitp2 = Pitp.dot(np.linalg.lstsq(P, y, rcond=None)[0])
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+
+class TestRBFInterpolatorNeighbors20(_TestRBFInterpolator):
+    # RBFInterpolator using 20 nearest neighbors.
+    def build(self, *args, **kwargs):
+        return RBFInterpolator(*args, **kwargs, neighbors=20)
+
+    def test_equivalent_to_rbf_interpolator(self):
+        seq = Halton(2, scramble=False, seed=np.random.RandomState())
+
+        x = seq.random(100)
+        xitp = seq.random(100)
+
+        y = _2d_test_function(x)
+
+        yitp1 = self.build(x, y)(xitp)
+
+        yitp2 = []
+        tree = cKDTree(x)
+        for xi in xitp:
+            _, nbr = tree.query(xi, 20)
+            yitp2.append(RBFInterpolator(x[nbr], y[nbr])(xi[None])[0])
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)
+
+
+class TestRBFInterpolatorNeighborsInf(TestRBFInterpolatorNeighborsNone):
+    # RBFInterpolator using neighbors=np.inf. This should give exactly the same
+    # results as neighbors=None, but it will be slower.
+    def build(self, *args, **kwargs):
+        return RBFInterpolator(*args, **kwargs, neighbors=np.inf)
+
+    def test_equivalent_to_rbf_interpolator(self):
+        seq = Halton(1, scramble=False, seed=np.random.RandomState())
+
+        x = 3*seq.random(50)
+        xitp = 3*seq.random(50)
+
+        y = _1d_test_function(x)
+        yitp1 = self.build(x, y)(xitp)
+        yitp2 = RBFInterpolator(x, y)(xitp)
+
+        assert_allclose(yitp1, yitp2, atol=1e-8)