# frexp(), frexpf(), frexpl()

Break a floating-point number into a normalized fraction and an integral power of 2

## Synopsis:

```#include <math.h>

double frexp( double value,
int* exp );

float frexpf( float value,
int* exp );

long double frexp( long double value,
int* exp );
```

## Arguments:

value
The value you want to break into a normalized fraction.
exp
A pointer to a location where the function can store the integral power of 2.

## Library:

libm

Use the -l m option to qcc to link against this library.

## Description:

These functions break a floating-point number into a normalized fraction and an integral power of 2. It stores the integral power of 2 in the int pointed to by exp.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

• Call feclearexcept(FE_ALL_EXCEPT) before calling frexp(), frexpf(), or frexpl().
• On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

## Returns:

A number, x, that has a magnitude in the interval [0.5, 1.0] or is 0.0, such that value = x * 2exp.

If value is: These functions return: *exp Errors:
±0.0 0.0, with the same sign as value 0
±Inf value Unspecified
NaN value Unspecified

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

## Examples:

```#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <fenv.h>

int main( void )
{
int expon;
double value;
int except_flags;

feclearexcept(FE_ALL_EXCEPT);
value = frexp(  4.25, &expon );
printf( "%f %d\n", value, expon );
except_flags = fetestexcept(FE_ALL_EXCEPT);
if(except_flags) {
/* An error occurred; handle it appropriately. */
}

feclearexcept(FE_ALL_EXCEPT);
value = frexp( -4.25, &expon );
printf( "%f %d\n", value, expon );
except_flags = fetestexcept(FE_ALL_EXCEPT);
if(except_flags) {
/* An error occurred; handle it appropriately. */
}

return EXIT_SUCCESS;
}
```

produces the output:

```0.531250 3
-0.531250 3
```

## Classification:

Safety:
Cancellation point No
Interrupt handler No
Signal handler No