ptypy.utils.math_utils.delxb#

ptypy.utils.math_utils.delxb(a, axis=-1)#

Backward first order derivative for finite difference calculation.

Note

The first element along the derivative direction is set to 0.

Pixel units are used (\(\Delta x = \Delta h = 1\)).

Parameters:

a (ndarray) – Input array.
axis (int, Default=-1, optional) – Which direction used for the derivative.

Returns:

out – Derived array.

Return type:

ndarray