Reduced row echelon form.
R = RREF(A) produces the reduced row echelon form of A.
[R,jb] = RREF(A) also returns a vector, jb, so that:
r = length(jb) is this algorithm's idea of the rank of A,
x(jb) are the bound variables in a linear system, Ax = b,
A(:,jb) is a basis for the range of A,
R(1:r,jb) is the r-by-r identity matrix.
[R,jb] = RREF(A,TOL) uses the given tolerance in the rank tests.
See also RREFMOVIE , RANK , ORTH , NULL , QR , SVD .