# LDEXP

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON

## NAME

ldexp, ldexpf,
ldexpl − multiply floating-point number by integral
power of 2

## SYNOPSIS

**#include
<math.h>**

**double
ldexp(double** *x***, int** *exp***); **

float ldexpf(float *x***, int** *exp***);
**

long double ldexpl(long double *x***, int**
*exp***);**

Link with
*−lm*.

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

**ldexpf**(),
**ldexpl**():

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

or *cc -std=c99*

## DESCRIPTION

The
**ldexp**() function returns the result of multiplying
the floating-point number *x* by 2 raised to the power
*exp*.

## RETURN VALUE

On success,
these functions return *x * (2^exp)*.

If *exp*
is zero, then *x* is returned.

If *x* is
a NaN, a NaN is returned.

If *x* is
positive infinity (negative infinity), positive infinity
(negative infinity) is returned.

If the result
underflows, a range error occurs, and zero is returned.

If the result
overflows, a range error occurs, and the functions return
**HUGE_VAL**, **HUGE_VALF**, or **HUGE_VALL**,
respectively, with a sign the same as *x*.

## ERRORS

See
**math_error**(7) for information on how to determine
whether an error has occurred when calling these
functions.

The following
errors can occur:

Range error, overflow

*errno* is set to
**ERANGE**. An overflow floating-point exception
(**FE_OVERFLOW**) is raised.

Range error, underflow

*errno* is set to
**ERANGE**. An underflow floating-point exception
(**FE_UNDERFLOW**) is raised.

## 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.

## SEE ALSO

**frexp**(3),
**modf**(3), **scalbln**(3)

## COLOPHON

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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/.