From “Reusing code and invertiing matrices” by Jack Crenshaw, Programmer's Toolbox, August 2008, ESD/ESP magazine.
This code file SimpleMat.cpp is a very simple set of matrix operations done in the old Fortran style. Its value lies in its efficiency. With the exception of a few asserts, no error checking is done. The user is expected to know what she's doing. Most importantly, there is no dynamic memory allocation — ever. The plan is to use these primitive functions as the basis for a proper C++ matrix class, but of course they can also be called directly.