A matrix times its inverse

A matrix times its inverse

Check the inverse: mat A times its inverse must give the identity matrix. Press on C, maths, 0, 0, and times. Then enter mat A again, maths, 0, 0, with second F and x to the minus 1, and equals. The rows are 1, 0, 0; then 0, 1, 0; then 0, 0, 1: the identity matrix. On the calculator, rounding can leave a very small number in place of a zero.