Ref And Rref
A matrix is in row echelon form (REF) if it has the following properties
All zero rows are at the bottom.
The leading entry in each row is to the right of the leading entry of the row above.
All entries below a leading entry are zero.
A matrix is in reduced row echelon form (RREF) if it is in REF form and in addition
All the leading entries are
. In this case, we call them “leading ones.” Each leading
is the only nonzero entry in its entire column.