float Q_rsqrt( float number ) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; i = 0x5f3759df - ( i >> 1 ); // ? y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); // y = y * ( threehalfs - ( x2 * y * y ) ); return y; }