Manual Reference Pages - LDEXP (3)
NAME
ldexp, ldexpf, ldexpl - multiply floating-point number by integral power of 2
CONTENTS
Synopsis
Description
Return Value
Errors
Colophon
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.

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
This page is part of release 3.44 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 /.

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