* for nonzero scalar
* if has orthonormal columns, where denotes the Moore-Penrose inverse and is a vector
*
* For any invertible -by- matrices and , More generally, if are invertible -by- matrices, then
*
*Left and right inverses are equal. That is, if and then .

The rows of the inverse matrix of a matrix are orthonormal to the columns of (and vice versa interchanging rows for columns). To see this, suppose