Â¬â€  Â¬â€  Â¬â€  Â¬â€  Â¬â€

# FREXP

Section: Linux Programmer's Manual (3)
Updated: 2008-10-29

## 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);
```

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

frexpf(), frexpl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; 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.

## 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);
} /* main */
```

ldexp(3), modf(3)

## COLOPHON

This page is part of release 3.21 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/.

## Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
EXAMPLE
Program source
COLOPHON

### Upcoming Linux Foundation Courses

30 Nov » 03 Dec - Virtual
2. LFS416 Linux Security
07 Dec » 10 Dec - Virtual
3. LFD411 Embedded Linux Development
07 Dec » 11 Dec - Atlanta

View All Upcoming Courses

### Who we are ?

The Linux Foundation is a non-profit consortium dedicated to the growth of Linux.

Frequent Questions