Converting between quaternions and rotation matrices johndcook.com/blog/2025/05/0…

“Cryptography is a mixture of mathematics and muddle, and without the muddle the mathematics can be used against you.” — Ian Cassels

How the eMudrha certificate debacle might have happened johndcook.com/blog/2026/10/2…

“Most of the problems in writing software come from not knowing what depends on what.” — Stuart Feldman, creator of make (1976)

'Writing code is often a constant struggle against distraction.' -- Joy of Clojure

Classic cryptography: The Playfair cipher johndcook.com/blog/2023/02/2…

Fitting a regular expression to a list of words johndcook.com/blog/2026/07/1…

Minimum criteria for a language to be Turing complete cs.stackexchange.com/questio…

Cardinal rule of floating point arithmetic: If x and y agree to n bits, then you can lose up to n bits of precision computing x-y.

Floor, ceiling, bracket johndcook.com/blog/2021/04/1…

'It has long been my personal view that the separation of practical and theoretical work is artificial and injurious.' -- Christopher Strachey

Algorithms to find which words can be spelled with chemical symbols. From O(n) to O(2^n). johndcook.com/blog/2026/10/1…

Alan Turing Found alluring Machines whose only fault Was that they would not halt. -- Karl David

AI-generated ASCII diagrams johndcook.com/blog/2026/08/2…

NIST curves exonerated Giving the backstory to the recent discovery of how the curves were seeded johndcook.com/blog/2026/10/1…

'The fastest algorithm can frequently be replaced by one that is almost as fast and much easier to understand.' -- Douglas W. Jones

C++ templates are Turing-complete matt.might.net/articles/c++-…

Mathematics for Computer Science cs.princeton.edu/courses/arc… [339 page pdf]

Eight fallacies of declarative computing johndcook.com/blog/2012/11/3…