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glibc  2.9
Functions | Variables
e_log10.c File Reference
#include "math.h"
#include "math_private.h"

Go to the source code of this file.

Functions

double __ieee754_log10 (double x)

Variables

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

Function Documentation

double __ieee754_log10 ( double  x)

Definition at line 72 of file e_log10.c.

{
       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/(x-x);             /* log(+-0)=-inf */
            if (hx<0) return (x-x)/(x-x); /* 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;
}

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Variable Documentation

double ivln10 = 4.34294481903251816668e-01 [static]

Definition at line 59 of file e_log10.c.

double log10_2hi = 3.01029995663611771306e-01 [static]

Definition at line 60 of file e_log10.c.

double log10_2lo = 3.69423907715893078616e-13 [static]

Definition at line 61 of file e_log10.c.

double two54 = 1.80143985094819840000e+16 [static]

Definition at line 58 of file e_log10.c.

double zero = 0.0 [static]

Definition at line 66 of file e_log10.c.