This guy is nuts: NEVER EVER write your own matrix multiplication routine! People have spent decades researching this problem. For all but the most trivial exam

This guy is nuts: NEVER EVER write your own matrix multiplication routine! People have spent decades researching this problem. For all but the most trivial examples, you WILL incur a performance penalty relative to the heavily optimized implementations that exist. Look up the source for `dgemm` in your favorite BLAS. Does it look like three for loops? No.