def body_fun(i, p_val):
coeff_0 = d0_mask_3d[i]
coeff_1 = d1_mask_3d[i]
h = (jnp.einsum(
'ij,ijk->ijk', coeff_0,
jnp.einsum('ijk,k->ijk', jnp.roll(p_val, shift=1, axis=1), x)) -
jnp.einsum('ij,ijk->ijk', coeff_1, jnp.roll(
p_val, shift=2, axis=1)))
p_val = p_val + h
return p_val
def _roots_with_zeros(p, num_leading_zeros):
# Avoid lapack errors when p is all zero
p = _where(len(p) == num_leading_zeros, 1.0, p)
# Roll any leading zeros to the end & compute the roots
roots = _roots_no_zeros(roll(p, -num_leading_zeros))
# Sort zero roots to the end.
roots = lax.sort_key_val(roots == 0, roots)[1]
# Set roots associated with num_leading_zeros to NaN
return _where(
arange(roots.size) < roots.size - num_leading_zeros, roots,
complex(np.nan, np.nan))
def ifftshift(x, axes=None):
x = jnp.asarray(x)
if axes is None:
axes = tuple(range(x.ndim))
shift = [-(dim // 2) for dim in x.shape]
elif isinstance(axes, int):
shift = -(x.shape[axes] // 2)
else:
shift = [-(x.shape[ax] // 2) for ax in axes]
return jnp.roll(x, shift, axes)
