#include "math_libm.h"
#include "math_private.h"

Include dependency graph for e_log10.c:

Functions
double attribute_hidden	__ieee754_log10 (double x)

Variables
static const double	two54 = 1.80143985094819840000e+16
static const double	ivln10 = 4.34294481903251816668e-01
static const double	log10_2hi = 3.01029995663611771306e-01
static const double	log10_2lo = 3.69423907715893078616e-13
static const double	zero = 0.0

Function Documentation

double attribute_hidden __ieee754_log10 ( double x )

Definition at line 61 of file e_log10.c.

References __ieee754_log, EXTRACT_WORDS, GET_HIGH_WORD, i, ivln10, k, log10_2hi, log10_2lo, SET_HIGH_WORD, two54, and zero.

{
        double y,z;
        int32_t i,k,hx;
        u_int32_t lx;
        EXTRACT_WORDS(hx,lx,x);
        k=0;
        if (hx < 0x00100000) {                  /* x < 2**-1022  */
            if (((hx&0x7fffffff)|lx)==0)
                return -two54/zero;             /* log(+-0)=-inf */
            if (hx<0) return (x-x)/zero;        /* log(-#) = NaN */
            k -= 54; x *= two54; /* subnormal number, scale up x */
            GET_HIGH_WORD(hx,x);
        }
        if (hx >= 0x7ff00000) return x+x;
        k += (hx>>20)-1023;
        i  = ((u_int32_t)k&0x80000000)>>31;
        hx = (hx&0x000fffff)|((0x3ff-i)<<20);
        y  = (double)(k+i);
        SET_HIGH_WORD(x,hx);
        z  = y*log10_2lo + ivln10*__ieee754_log(x);
        return  z+y*log10_2hi;
}