## Comment: The ultimate ugly hack? (Score 5, Insightful) 264

Fast inverse square root (sometimes referred to as Fast InvSqrt() or by the hexadecimal constant 0x5f3759df) is a method of calculating x1/2, the reciprocal (or multiplicative inverse) of a square root for a 32-bit floating point number in IEEE 754 floating point format.

http://en.wikipedia.org/wiki/F...

Anybody got any better Ugly Hacks to share?