FREXP

Section: Linux Programmer's Manual (3)
Updated: 2002-07-27
Index Return to Main Contents

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);

Link with -lm.

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 its absolute value 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

SVr4, 4.3BSD, C89. The float and long double variants are C99 requirements.

EXAMPLE


#include <math.h>

#include <float.h>

#include <stdio.h>

#include <stdlib.h>



int

main(int argc, char *argv[])

{

    double x, r;

    int exp;



    x = strtod(argv[1], NULL);

    r = frexp(x, &exp);



    printf("frexp(%g, &e) = %g: %g * %d^%d = %g\n",

           x, r, r, FLT_RADIX, exp, x);

    exit(EXIT_SUCCESS);

} /* main */

This program produces results such as the following:

$ ./a.out 2560 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 $ ./a.out -4 frexp(-4, &e) = -0.5: -0.5 * 2^3 = -4

This document was created by man2html, using the manual pages.
Time: 22:14:55 GMT, February 02, 2008