## 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`)`;

Note
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`
Note 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), 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.

No errors occur.

## ATTRIBUTES

The `frexp`(), `frexpf`(), and `frexpl`() functions are thread-safe.

## 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);
}
```

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