Here are some practices that you may find helpful when working with matrices in Sage.

Break the matrix entries across lines, one for each row, for better readability by pressing

*Enter*between rows.A = matrix(2, 4, [ 1, 2, -1, 0, -3, 0, 4, 3 ])

Print your original matrix to check that you have entered it correctly. You may want to also print a dividing line to separate matrices.

A = matrix(2, 2, [ 1, 2, 2, 2]) print A print "---------" A.rref()