The Quake III Fast Inverse Square Root Explained
Nemean · Explainer · 20 min · 2020 · YouTube title: Fast Inverse Square Root — A Quake III Algorithm
Why it's here
HN recommends it as an approachable explanation that makes the famous algorithm finally make sense.
What it covers
A walkthrough of the Quake III fast inverse square root, explaining where the constant 0x5f3759df comes from. It covers IEEE 754 floats, the bit hack that approximates a logarithm, and a Newton's method refinement.