Christian Reinsch and Roland Bulirsch both passed away recently, Reinsch on October 8 and Bulirsch on September 21. Reinsch was 88 years old and Bulirsch was 89. Both of them were retired professors of numerical analysis at the Technical University of Munich. Both of them were friends of mine. But in almost all other ways, they were very different people.... read more >>

I do not recall having seen this matrix before, but I will not be surprised to learn that somebody else already knows all about it, especially if that person's name is Nick.... read more >>

This blog post describes Qube, my Rubik's Cube simulator. Source code for Qube is now available in one single file from this link: Qube_osf.m. I will also submit the code to the MATLAB Central File Exchange. As usual, I welcome any feedback.... read more >>

Rubik's Cube is one of the great mathematical puzzles of all time. Most people are just interested in solving Rubik's Cube rapidly, but deeper investigation reveals a rich mathematical and computational structure. A digital Rubik's Cube simulator provides a laboratory for the study of linear algebra, group theory, data structures and computer graphics.... read more >>

The answer: A\A is always I, except when it isn't.... read more >>

My recent obsession with cubes in this blog has led me back to Rubik's cube, perhaps the greatest mathematical puzzle of all time.... read more >>

Matrices in action.... read more >>

See Cube and Teapot.... read more >>