A faster way to calculate the day-of-the-week
Summary
Explains a range of high-performance algorithms for converting rata-die day counts to weekday values, including 32-bit and 64-bit variants and a fast mul-add-shift approach. The piece emphasizes throughput, compiler behavior, and portability, with examples and a MIT-licensed reference implementation. It also situates these methods in the broader context of date libraries and benchmarking.