Something wrong with 'gaussian_fn'

[zhuzhenxi]

'gaussian_fn' doesn't even use the value of 'sigma'?
Line 61 of https://github.com/jolaem/Gabor3D/blob/master/gabor.py, should it be
g = np.exp(- ((x/float(sigma)) ** 2 / 2 + (y/float(sigma)) ** 2 / 2 + (z/float(sigma)) ** 2 / 2)) ?