sigpy.mri.circulant_precond

sigpy.mri.circulant_precond(mps, weights=None, coord=None, lamda=0, device=<CPU Device>)

Compute circulant preconditioner.

Considers the optimization problem:

\[\min_P \| A^H A - F P F^H \|_2^2\]

where A is the Sense operator, and F is a unitary Fourier transform operator.

Parameters:

• mps (array) – sensitivity maps of shape [num_coils] + image shape.
• weights (array) – k-space weights.
• coord (array) – k-space coordinates of shape […] + [ndim].
• lamda (float) – regularization.

Returns:

circulant preconditioner of image shape.

Return type:

array