Lake Arrowhead Coauthor Graph Revisited

Posted by Cleve Moler,

The Lake Arrowhead Coauthor Graph came out of the Householder XII conference in 1993 at the UCLA conference center in the mountains north of San Bernardino. John Gilbert now remembers it as one of the first computational social network analyses he had ever seen. Today I revisit it using the new MATLAB graph object.... read more >>

Patience Chinese Rings Puzzle

Posted by Cleve Moler,

MIT's Professor Daniel Frey recently introduced me to an ancient mechanical puzzle known as "Chinese Rings", "Patience", or "Baguenaudier." I have modified Daniel's simulator to produce a new app. The state space of the puzzle forms a hypercube.... read more >>

Ulps Plots Reveal Math Function Accuracy 2

Posted by Cleve Moler,

"ULP" stands for "unit in the last place." An ulps plot samples a fundamental math function such as $\sin{x}$, or a more esoteric function like a Bessel function. The samples are compared with more accurate values obtained from a higher precision computation. A plot of the accuracy, measured in ulps, reveals valuable information about the underlying algorithms.... read more >>

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