how to make a matrix elements randomly distributed

how to make a matrix m elements, which has n elements "one" or #0, randomly distributed, the remaining elements are zero (n<m).

Answer 1

[David Sanchez]

Try this out (adapt the values to your needs):

m = 10;
n = 3;
pos = randperm(m*n,m);
M = zeros(m,n);
M(pos) = 1;

M =

     0     0     0
     1     1     0
     0     1     1
     0     0     0
     1     0     0
     0     0     0
     0     0     0
     1     0     1
     0     1     1
     0     0     1

M has the ones randomly distributed.

[Jan]

And for older Matlab versions:

M   = zeros(m,n);
pos = randperm(m*n);
M(pos(1:n)) = 1;

Answer 2

[Pham Ngoc Thanh]

thanks a lot.