sqrt_data.h raw

   1  #ifndef _SQRT_DATA_H
   2  #define _SQRT_DATA_H
   3  
   4  #include <features.h>
   5  #include <stdint.h>
   6  
   7  /* if x in [1,2): i = (int)(64*x);
   8     if x in [2,4): i = (int)(32*x-64);
   9     __rsqrt_tab[i]*2^-16 is estimating 1/sqrt(x) with small relative error:
  10     |__rsqrt_tab[i]*0x1p-16*sqrt(x) - 1| < -0x1.fdp-9 < 2^-8 */
  11  extern hidden const uint16_t __rsqrt_tab[128];
  12  
  13  #endif
  14