Fixed database typo and removed unnecessary class identifier.

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

@@ -0,0 +1,115 @@
+"""
+Precompute coefficients of Temme's asymptotic expansion for gammainc.
+
+This takes about 8 hours to run on a 2.3 GHz Macbook Pro with 4GB ram.
+
+Sources:
+[1] NIST, "Digital Library of Mathematical Functions",
+    https://dlmf.nist.gov/
+
+"""
+import os
+from scipy.special._precompute.utils import lagrange_inversion
+
+try:
+    import mpmath as mp  # type: ignore[import]
+except ImportError:
+    pass
+
+
+def compute_a(n):
+    """a_k from DLMF 5.11.6"""
+    a = [mp.sqrt(2)/2]
+    for k in range(1, n):
+        ak = a[-1]/k
+        for j in range(1, len(a)):
+            ak -= a[j]*a[-j]/(j + 1)
+        ak /= a[0]*(1 + mp.mpf(1)/(k + 1))
+        a.append(ak)
+    return a
+
+
+def compute_g(n):
+    """g_k from DLMF 5.11.3/5.11.5"""
+    a = compute_a(2*n)
+    g = [mp.sqrt(2)*mp.rf(0.5, k)*a[2*k] for k in range(n)]
+    return g
+
+
+def eta(lam):
+    """Function from DLMF 8.12.1 shifted to be centered at 0."""
+    if lam > 0:
+        return mp.sqrt(2*(lam - mp.log(lam + 1)))
+    elif lam < 0:
+        return -mp.sqrt(2*(lam - mp.log(lam + 1)))
+    else:
+        return 0
+
+
+def compute_alpha(n):
+    """alpha_n from DLMF 8.12.13"""
+    coeffs = mp.taylor(eta, 0, n - 1)
+    return lagrange_inversion(coeffs)
+
+
+def compute_d(K, N):
+    """d_{k, n} from DLMF 8.12.12"""
+    M = N + 2*K
+    d0 = [-mp.mpf(1)/3]
+    alpha = compute_alpha(M + 2)
+    for n in range(1, M):
+        d0.append((n + 2)*alpha[n+2])
+    d = [d0]
+    g = compute_g(K)
+    for k in range(1, K):
+        dk = []
+        for n in range(M - 2*k):
+            dk.append((-1)**k*g[k]*d[0][n] + (n + 2)*d[k-1][n+2])
+        d.append(dk)
+    for k in range(K):
+        d[k] = d[k][:N]
+    return d
+
+
+header = \
+r"""/* This file was automatically generated by _precomp/gammainc.py.
+ * Do not edit it manually!
+ */
+
+#ifndef IGAM_H
+#define IGAM_H
+
+#define K {}
+#define N {}
+
+static const double d[K][N] =
+{{"""
+
+footer = \
+r"""
+#endif
+"""
+
+def main():
+    print(__doc__)
+    K = 25
+    N = 25
+    with mp.workdps(50):
+        d = compute_d(K, N)
+    fn = os.path.join(os.path.dirname(__file__), '..', 'cephes', 'igam.h')
+    with open(fn + '.new', 'w') as f:
+        f.write(header.format(K, N))
+        for k, row in enumerate(d):
+            row = map(lambda x: mp.nstr(x, 17, min_fixed=0, max_fixed=0), row)
+            f.write('{')
+            f.write(", ".join(row))
+            if k < K - 1:
+                f.write('},\n')
+            else:
+                f.write('}};\n')
+        f.write(footer)
+    os.rename(fn + '.new', fn)
+
+
+if __name__ == "__main__":
+    main()