41 lines
1.1 KiB
Python
41 lines
1.1 KiB
Python
import numpy as np
|
|
from scipy.special import legendre
|
|
import libsharp
|
|
|
|
from numpy.testing import assert_allclose
|
|
|
|
|
|
def check_legendre_transform(lmax, ntheta):
|
|
l = np.arange(lmax + 1)
|
|
if lmax >= 1:
|
|
sigma = -np.log(1e-3) / lmax / (lmax + 1)
|
|
bl = np.exp(-sigma*l*(l+1))
|
|
bl *= (2 * l + 1)
|
|
else:
|
|
bl = np.asarray([1], dtype=np.double)
|
|
|
|
theta = np.linspace(0, np.pi, ntheta, endpoint=True)
|
|
x = np.cos(theta)
|
|
|
|
# Compute truth using scipy.special.legendre
|
|
P = np.zeros((ntheta, lmax + 1))
|
|
for l in range(lmax + 1):
|
|
P[:, l] = legendre(l)(x)
|
|
y0 = np.dot(P, bl)
|
|
|
|
|
|
# double-precision
|
|
y = libsharp.legendre_transform(x, bl)
|
|
|
|
assert_allclose(y, y0, rtol=1e-12, atol=1e-12)
|
|
|
|
# single-precision
|
|
y32 = libsharp.legendre_transform(x.astype(np.float32), bl)
|
|
assert_allclose(y, y0, rtol=1e-5, atol=1e-5)
|
|
|
|
|
|
def test_legendre_transform():
|
|
nthetas_to_try = [0, 9, 17, 19] + list(np.random.randint(500, size=20))
|
|
for ntheta in nthetas_to_try:
|
|
for lmax in [0, 1, 2, 3, 20] + list(np.random.randint(50, size=4)):
|
|
yield check_legendre_transform, lmax, ntheta
|