Need the Inverse Square Root of a Number, Fast?
by Marshall on December 1, 2006
Quake 3 has a the following bit of code to calculate the inverse square of an integer.
The i = 0x5f3759df - (i >> 1); is the most curious part of the function, and apparently is has to do with Newton’s Method, which is an efficient way to approximate the roots of a function.
( via Slashdot )
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