LDEXP
LDEXP
Section: Linux Programmer's Manual (3) Updated: 2010-09-20 Local index
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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,
an 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 3.27 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/.

Index
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
COLOPHON
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Time: 21:49:04 GMT, April 16, 2011