Quake 3’s Fast Inverse Square Root Function

Note: This is not meant to be an authoritative mathematical description, and I’m pretty late to the party.. I was experimenting with the code, and am scratching an itch. For a far superior description, please look at Chris Lomont’s excellent analysis.
The Infamous Code

x2 = number * 0.5F;
y = number;
i = * ( long [...]

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