computes matrix row echelon form by lu transformations
R=rref(A)
:A m x n matrix with scalar entries : :R m x n matrix,row echelon form of a :
rref computes the row echelon form of the given matrix by left lu decomposition. If ones need the transformation used just call X=rref([A,eye(m,m)]) the row echelon form R is X(:,1:n) and the left transformation L is given by X(:,n+1:n+m) such as L*A=R
A=[1 2;3 4;5 6];
X=rref([A,`eye`_(3,3)]);
R=X(:,1:2)
L=X(:,3:5);L*A