Efficient function implementation for solving the reciprocal of square root

/*** Float q_rsqrt (float number) */float q_rsqrt (float number) {long I; float X2, Y; const float threehalfs = 1.5f; x2 = Number * 0.5f; y = number; I = * (long *) & Y; // edevil floating point bit level hackingi = 0x5f3759df-(I> 1); // What the fuck? Y = * (float *) & I; y = y * (threehalfs-(X2 * y )); // 1st iteration // y = y * (threehalfs-(X2 * y); // 2nd iteration, this can be removed # ifdef _ Linux _ assert (! Isnan (y); // bk010122-FPE? # Endifreturn y ;}

 

Efficient function implementation for solving the reciprocal of square root