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                    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 ****?
  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;
}