L()

function out=L(in)

Input:

• in: $N_s$ sets of $d=3$ dimensional data, stored as an $\prod S_k\,\times\,N_s$ matrix

Global variables:

• gbl_S: dimensions of $d=3$ dimensional data sets

Output:

• out: L operator applied to in

Generalize the software in your file ``L.m'' according to the above prototype. One option would be to follow the same procedure you used to generalize ``cI.m''. However, a computationally quicker option (but one which uses more memory) is to use BLAS operations to expand G2 into a matrix each of whose columns contains a copy of G2, as may be accomplished with ``gbl_G2*ones(1,size(in,2))''. Then you may use the ``.*'' operator to compute the output using a statement containing the fragment ``gbl_G2*ones(1,size(in,2)).*in''.
Hint: Don't forget all of the other important factors!