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Manual Reference Pages  - FREXP (3)

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

CONTENTS

Synopsis
Description
Example

#include <math.h> 



double frexp(double x, int *exp); 



float frexpf(float x, int *exp); 



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

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

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.

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

#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

ldexp(3), modf(3)

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