# FREXP

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

EXAMPLE

SEE ALSO

COLOPHON

## 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*.

Feature Test
Macro Requirements for glibc (see
**feature_test_macros**(7)):

**frexpf**(),
**frexpl**():

_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;

or *cc -std=c99*

## 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), that
is, [0.5,1).

If *x* is
zero, then the normalized fraction is zero and zero is
stored in *exp*.

If *x* is
a NaN, a NaN is returned, and the value of **exp* is
unspecified.

If *x* is
positive infinity (negative infinity), positive infinity
(negative infinity) is returned, and the value of
**exp* is unspecified.

## ERRORS

No errors
occur.

## ATTRIBUTES

For an
explanation of the terms used in this section, see
**attributes**(7).

## CONFORMING TO

C99,
POSIX.1-2001. The variant returning *double* also
conforms to SVr4, 4.3BSD, C89.

## EXAMPLE

The program
below 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

**Program
source**

#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);

}

## SEE ALSO

**ldexp**(3),
**modf**(3)

## COLOPHON

This page is
part of release 3.53 of the Linux *man-pages* project.
A description of the project, and information about
reporting bugs, can be found at
http://www.kernel.org/doc/man−pages/.