FREXP(3)

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)