grad_tv¶

Gradient of total variation term for gradient descent update.

mr_utils.utils.grad_tv.dTV(A, eps=1e-08)[source]¶

Compute derivative of the TV with respect to the matrix A.

Parameters:	A (array_like) – 2d matrix (can be complex). eps (float, optional) – small positive constant used to avoid a divide by zero.
Returns:	Derivative of TV w.r.t. A.
Return type:	array_like

Notes

Implements Equation [13] from [1].

References

[1]	Zhang, Yan, Yuanyuan Wang, and Chen Zhang. “Total variation based gradient descent algorithm for sparse-view photoacoustic image reconstruction.” Ultrasonics 52.8 (2012): 1046-1055.