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