README.md

float Q_rsqrt(float number) {
    long i;
    float x2, y;
    const float threehalfs = 1.5F;

    x2 = number * 0.5F;
    y  = number;
    i  = * (long*) &y;                          // evil floating point bit level hacking
    i  = 0x5f3759df - (i >> 1);                 // what the fuck?
    y  = * (float*) &i;
    y  = y * (threehalfs - (x2 * y * y));       // 1st iteration
//      y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}