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)

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

Note: gradients are assumed to be linear and centered on the
      middle of the sample.

Note: the direct product order is Z(x)Y(x)X(x)Spin, this cor-
      responds to a column-wise vectorization of a 3D array
      with dimensions ordered as [X Y Z].

Note: polyadic objects are returned, use inflate() to get the
      corresponding sparse matrix.

a.j.allami@soton.ac.uk
ilya.kuprov@weizmann.ac.il
mariagrazia.concilio@sjtu.edu.cn

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.

See also

v2fplanck.m, hydrodynamics.m, imaging.m

Version 2.1, authors: Ilya Kuprov, Ahmed Allami

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.