frexp(3) -- Linux man page

 

NAME

frexp, frexpf, frexpl - convert floating-point number to fractional and integral components  

SYNOPSIS

#include <math.h>

double frexp(double x, int *exp);

float frexpf(float x, int *exp);

long double frexpl(long double x, int *exp);
 

DESCRIPTION

The frexp() function is used to split the number x into a normalized fraction and an exponent which is stored in exp.  

RETURN VALUE

The frexp() function returns the normalized fraction. If the argument x is not zero, the normalized fraction is x times a power of two, and is always in the range 1/2 (inclusive) to 1 (exclusive). If x is zero, then the normalized fraction is zero and zero is stored in exp.  

CONFORMING TO

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and the long double variants are C99 requirements.  

EXAMPLE

#include <stdio.h>
#include <math.h>
#include <float.h>
int main () {
        double d = 2560;
        int e;
        double f = frexp(d, &e);
        printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",
               d, f, f, FLT_RADIX, e, d);
        return 0;
}

This program prints

frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560  

SEE ALSO

ldexp(3), modf(3)