Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/special/_precompute/gammainc_data.py

@@ -0,0 +1,124 @@
+"""Compute gammainc and gammaincc for large arguments and parameters
+and save the values to data files for use in tests. We can't just
+compare to mpmath's gammainc in test_mpmath.TestSystematic because it
+would take too long.
+
+Note that mpmath's gammainc is computed using hypercomb, but since it
+doesn't allow the user to increase the maximum number of terms used in
+the series it doesn't converge for many arguments. To get around this
+we copy the mpmath implementation but use more terms.
+
+This takes about 17 minutes to run on a 2.3 GHz Macbook Pro with 4GB
+ram.
+
+Sources:
+[1] Fredrik Johansson and others. mpmath: a Python library for
+    arbitrary-precision floating-point arithmetic (version 0.19),
+    December 2013. http://mpmath.org/.
+
+"""
+import os
+from time import time
+import numpy as np
+from numpy import pi
+
+from scipy.special._mptestutils import mpf2float
+
+try:
+    import mpmath as mp  # type: ignore[import]
+except ImportError:
+    pass
+
+
+def gammainc(a, x, dps=50, maxterms=10**8):
+    """Compute gammainc exactly like mpmath does but allow for more
+    summands in hypercomb. See
+
+    mpmath/functions/expintegrals.py#L134
+
+    in the mpmath github repository.
+
+    """
+    with mp.workdps(dps):
+        z, a, b = mp.mpf(a), mp.mpf(x), mp.mpf(x)
+        G = [z]
+        negb = mp.fneg(b, exact=True)
+
+        def h(z):
+            T1 = [mp.exp(negb), b, z], [1, z, -1], [], G, [1], [1+z], b
+            return (T1,)
+
+        res = mp.hypercomb(h, [z], maxterms=maxterms)
+        return mpf2float(res)
+
+
+def gammaincc(a, x, dps=50, maxterms=10**8):
+    """Compute gammaincc exactly like mpmath does but allow for more
+    terms in hypercomb. See
+
+    mpmath/functions/expintegrals.py#L187
+
+    in the mpmath github repository.
+
+    """
+    with mp.workdps(dps):
+        z, a = a, x
+
+        if mp.isint(z):
+            try:
+                # mpmath has a fast integer path
+                return mpf2float(mp.gammainc(z, a=a, regularized=True))
+            except mp.libmp.NoConvergence:
+                pass
+        nega = mp.fneg(a, exact=True)
+        G = [z]
+        # Use 2F0 series when possible; fall back to lower gamma representation
+        try:
+            def h(z):
+                r = z-1
+                return [([mp.exp(nega), a], [1, r], [], G, [1, -r], [], 1/nega)]
+            return mpf2float(mp.hypercomb(h, [z], force_series=True))
+        except mp.libmp.NoConvergence:
+            def h(z):
+                T1 = [], [1, z-1], [z], G, [], [], 0
+                T2 = [-mp.exp(nega), a, z], [1, z, -1], [], G, [1], [1+z], a
+                return T1, T2
+            return mpf2float(mp.hypercomb(h, [z], maxterms=maxterms))
+
+
+def main():
+    t0 = time()
+    # It would be nice to have data for larger values, but either this
+    # requires prohibitively large precision (dps > 800) or mpmath has
+    # a bug. For example, gammainc(1e20, 1e20, dps=800) returns a
+    # value around 0.03, while the true value should be close to 0.5
+    # (DLMF 8.12.15).
+    print(__doc__)
+    pwd = os.path.dirname(__file__)
+    r = np.logspace(4, 14, 30)
+    ltheta = np.logspace(np.log10(pi/4), np.log10(np.arctan(0.6)), 30)
+    utheta = np.logspace(np.log10(pi/4), np.log10(np.arctan(1.4)), 30)
+
+    regimes = [(gammainc, ltheta), (gammaincc, utheta)]
+    for func, theta in regimes:
+        rg, thetag = np.meshgrid(r, theta)
+        a, x = rg*np.cos(thetag), rg*np.sin(thetag)
+        a, x = a.flatten(), x.flatten()
+        dataset = []
+        for i, (a0, x0) in enumerate(zip(a, x)):
+            if func == gammaincc:
+                # Exploit the fast integer path in gammaincc whenever
+                # possible so that the computation doesn't take too
+                # long
+                a0, x0 = np.floor(a0), np.floor(x0)
+            dataset.append((a0, x0, func(a0, x0)))
+        dataset = np.array(dataset)
+        filename = os.path.join(pwd, '..', 'tests', 'data', 'local',
+                                '{}.txt'.format(func.__name__))
+        np.savetxt(filename, dataset)
+
+    print("{} minutes elapsed".format((time() - t0)/60))
+
+
+if __name__ == "__main__":
+    main()