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A Fast 64-Bit Date Algorithm (30–40% faster by counting dates backwards)
Counting years backwards unlocks faster speed. The first date algorithm to use only 4 multiplications, instead of 7+
Ben Joffe
I am software developer in Sydney. Recently, in my spare time I have worked on computer algorithms for calendar-date and timestamp conversion, for both Earth and Mars. Some of these algorithms are the fastest in their class, and have been adopted by LLVM and Webkit.
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Visit benjoffe.com → RSS feedOn Hacker News Nov 2025 – Oct 2026
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A faster way to calculate the day of the week
A range of fast modulus techniques that beat compiler output
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A new faster algorithm to compute 64-bit signed floor division
The missing chapter of Hacker's Delight