# frexp(3) — Linux manual page

```FREXP(3)                  Linux Programmer's Manual                 FREXP(3)
```

## NAME         top

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

## SYNOPSIS         top

```       #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():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
```

## DESCRIPTION         top

```       These functions are used to split the number x into a normalized
fraction and an exponent which is stored in exp.
```

## RETURN VALUE         top

```       These functions return 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         top

```       No errors occur.
```

## ATTRIBUTES         top

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

┌────────────────────────────┬───────────────┬─────────┐
│Interface                   │ Attribute     │ Value   │
├────────────────────────────┼───────────────┼─────────┤
│frexp(), frexpf(), frexpl() │ Thread safety │ MT-Safe │
└────────────────────────────┴───────────────┴─────────┘
```

## CONFORMING TO         top

```       C99, POSIX.1-2001, POSIX.1-2008.

The variant returning double also conforms to SVr4, 4.3BSD, C89.
```

## EXAMPLES         top

```       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, 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);
}
```

```       ldexp(3), modf(3)
```

## COLOPHON         top

```       This page is part of release 5.08 of the Linux man-pages project.  A
description of the project, information about reporting bugs, and the