jmat

Arguments

n

number of block rows or block columns of the matrix

m

size of the (square) blocks

j

(m*n,m*n) matrix with m*m eyed blocks

Description

This function yields a square matrix j of size (m*n, m*n) that can be used for permuting the n blocks of m consecutive columns of a (m*n, m*n) square matrix W by W*j. For permuting the n blocks of m consecutive rows, use: j'*W

Example

m=grand(4,4,"uin",0,9).*.ones(2,2)
j=jmat(4,2)
m*j   // permutes blocks of columns
j'*m  // permutes blocks of rows