You might have wondered why the authors of supermongo have only implemented matrix routines for quadratic matrices in their standard macros (see help matrix in supermongo for details). So have I. In case this helps you, feel free to use the following generalizations of some matrix macros to n x m - matrices. I only implemented those I needed and did some testing on them, this is not a complete set of what you might require. The macros are named like the usual ones, but with a suffix "2".

matrix2 (sm, 2 KB)