MATDIFF Difference between vectors
d_ij = matdiff(Xi,Xj)
INPUTS:
Xi,Xj: Data matrices of size (R,NXi) and (R,NXj) composed by column
vectors of size (R,1).
d_ij: Matrix (R,NXi*NXj) with difference vectors
DESCRIPTION:
d_ij, contains a matrix with difference vectors Xi-Xj placed by
columns such that reshape(d_ij(k,:)) gives a matrix whose element
(i,j) is the difference between the k-coordinates of Xi and Xj