MATLAB: Maximizing efficiency in simple commands

Question

I have an array given by

x = [1 2 3 4];

I would like to create a matrix that looks like

M = [1 2 3 4;
     1 2 3 4;
     1 2 3 4;
     1 2 3 4];

What's the most computationally efficient way to create M from x?

Answer 1

x=[1 2 3 4]; 
M=repmat(x,4,1)