row echelon form

Summary

REF(row echelon form)

• nonzero rows are above any all-zero rows
• each leading entry of a row is in a column right of the leading entry of the row above
• all entries before a leading entry are zeros

RREF(reduced row echelon form)

• leading entry in each row is 1
• leading 1 is the only nonzero entry in its column

Pivot columns

• columns with leading entries in the reduced echelon form