LDEXP
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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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():
-
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
These functions return 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).
| Interface | Attribute | Value
|
|
ldexp(),
ldexpf(),
ldexpl()
| Thread safety | MT-Safe
|
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
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 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- CONFORMING TO
-
- SEE ALSO
-
- COLOPHON
-
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- Running on 
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