Repmat is not a built-in function in Matlab. It is slow. An alternative is to do “repmat” by matlab indexing, which is faster.

x=[1 2 3 4]' ;
x(:, ones(4,1));%repmat(x, [1 4]) ;
x=[1 2 3 4];
x(ones(1,4),:);%repmat(x,[4 1])

A more detailed tutorial is found here.