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Robustify cart2sph() function #24

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Robustify cart2sph() function #24

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11 changes: 4 additions & 7 deletions gradunwarp/core/unwarp_resample.py
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Original file line number Diff line number Diff line change
Expand Up @@ -356,15 +356,12 @@ def eval_spherical_harmonics(coeffs, vendor, vxyz):

return CV(bx * R0, by * R0, bz * R0), CV(x, y, z)


# Convert to spherical coordinates
def cart2sph(x1, y1, z1):
x1 = x1 + 0.0001 # hack to avoid singularities at R=0
# convert to spherical coordinates
r = np.sqrt(x1 * x1 + y1 * y1 + z1 * z1)
cosine_theta = z1 / r
r = np.hypot(np.hypot(x1, y1), z1)
cosine_theta = z1 / np.where(r != 0.0, r, 1.0)
theta = np.arccos(cosine_theta)
phi = np.arctan2(y1 / r, x1 / r)

phi = np.arctan2(y1, x1)
return r, cosine_theta, theta, phi

def siemens_B(alpha, beta, r, cosine_theta, theta, phi, R0):
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