Matlab Tricks

1. Repeat rows in matrix separately

a = [1 2 3;4 5 6] ; % original matrix
a =

     1     2     3
     4     5     6

N = 2 ; % number of repetitions
b = a(repmat(1:size(a,1),N,1),:) ; % new matrix
b =

     1     2     3
     1     2     3
     4     5     6
     4     5     6