# g2fplanck.m

Returns magnetic field gradient operators within the Fokker-Planck formalism used in the imaging module of Spinach.

## Syntax

    G=g2fplanck(spin_system,parameters)


## Description

The cell array contains {Gx,Gy,Gz}, which should simply be added to the Hamiltonian with appropriate coefficients. Gradients are assumed to be linear and centered on the middle of the sample.

## Arguments

  parameters.dims    - a vector with one, two or three
elements giving the dimensions
of the box, metres

parameters.npts    - a vector with one, two or three
elements giving number of points
in each dimension of the box


## Outputs

  G - a cell array with the three gradient operators
ordered as {Gx,Gy,Gz}, normalised to 1 T/m, empty
matrices for non-exitent dimensions


## Notes

1. The direct product order is Z(x)Y(x)X(x)Spin, this corresponds to a column-wise vectorization of a 3D array with dimensions ordered as [X Y Z].

2. Polyadic objects are returned, use polyadic/inflate.m to get the corresponding sparse matrix.