I guess you are looking for the nontrivial solution. I think you should solve it So, I am sure that Matlab has a function to put a matrix in row reduced echelon form. Create a matrix with A columns and the last column being all zeros. I know this is of limited help, but your question seems vague.
So you need to make a matrix. Say it is four by four. Then here is the code:
each semicolon separates a column of the matrix.
A = [1 2 3 4; 1 2 3 4; 1 2 3 4; 0 0 0 0];
rref(A);