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Jul 27th, 2016
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  1. float Q_rsqrt( float number )
  2. {
  3. long i;
  4. float x2, y;
  5. const float threehalfs = 1.5F;
  6.  
  7. x2 = number * 0.5F;
  8. y = number;
  9. i = * ( long * ) &y; // evil floating point bit level hacking
  10. i = 0x5f3759df - ( i >> 1 ); // what the fuck?
  11. y = * ( float * ) &i;
  12. y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
  13. // y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed
  14.  
  15. return y;
  16. }
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