You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
55 lines
1.3 KiB
Python
55 lines
1.3 KiB
Python
"""Precompute the polynomials for the asymptotic expansion of the
|
|
generalized exponential integral.
|
|
|
|
Sources
|
|
-------
|
|
[1] NIST, Digital Library of Mathematical Functions,
|
|
https://dlmf.nist.gov/8.20#ii
|
|
|
|
"""
|
|
import os
|
|
|
|
try:
|
|
import sympy # type: ignore[import]
|
|
from sympy import Poly
|
|
x = sympy.symbols('x')
|
|
except ImportError:
|
|
pass
|
|
|
|
|
|
def generate_A(K):
|
|
A = [Poly(1, x)]
|
|
for k in range(K):
|
|
A.append(Poly(1 - 2*k*x, x)*A[k] + Poly(x*(x + 1))*A[k].diff())
|
|
return A
|
|
|
|
|
|
WARNING = """\
|
|
/* This file was automatically generated by _precompute/expn_asy.py.
|
|
* Do not edit it manually!
|
|
*/
|
|
"""
|
|
|
|
|
|
def main():
|
|
print(__doc__)
|
|
fn = os.path.join('..', 'cephes', 'expn.h')
|
|
|
|
K = 12
|
|
A = generate_A(K)
|
|
with open(fn + '.new', 'w') as f:
|
|
f.write(WARNING)
|
|
f.write("#define nA {}\n".format(len(A)))
|
|
for k, Ak in enumerate(A):
|
|
tmp = ', '.join([str(x.evalf(18)) for x in Ak.coeffs()])
|
|
f.write("static const double A{}[] = {{{}}};\n".format(k, tmp))
|
|
tmp = ", ".join(["A{}".format(k) for k in range(K + 1)])
|
|
f.write("static const double *A[] = {{{}}};\n".format(tmp))
|
|
tmp = ", ".join([str(Ak.degree()) for Ak in A])
|
|
f.write("static const int Adegs[] = {{{}}};\n".format(tmp))
|
|
os.rename(fn + '.new', fn)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|