29 lines
727 B
Python
29 lines
727 B
Python
import numpy as np
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from scipy.special import legendre
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import libsharp
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def test_legendre_transform():
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lmax = 20
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ntheta = 19
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l = np.arange(lmax + 1)
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bl = np.exp(-l*(l+1))
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bl *= (2 * l + 1)
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theta = np.linspace(0, np.pi, ntheta, endpoint=True)
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x = np.cos(theta)
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# Compute truth using scipy.special.legendre
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P = np.zeros((ntheta, lmax + 1))
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for l in range(lmax + 1):
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P[:, l] = legendre(l)(x)
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y0 = np.dot(P, bl)
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# double-precision
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y = libsharp.legendre_transform(x, bl)
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assert np.max(np.abs(y - y) / np.abs(y)) < 1e-12
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# single-precision
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y32 = libsharp.legendre_transform(x.astype(np.float32), bl)
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assert np.max(np.abs(y32 - y) / np.abs(y32)) < 1e-4
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