table of contents
other versions
- jessie 3.74-1
- jessie-backports 4.10-2~bpo8+1
- stretch 4.10-2
- testing 4.16-1
- stretch-backports 4.16-1~bpo9+1
- unstable 4.16-1
LDEXP(3) | Linux Programmer's Manual | LDEXP(3) |
NAME¶
ldexp, ldexpf, ldexpl - multiply floating-point number by integral power of 2SYNOPSIS¶
#include <math.h> double ldexp(double x, int exp);Link with -lm.float ldexpf(float x, int exp);long double ldexpl(long double x, int exp);
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
|| /* 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 4.10 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/.2016-03-15 |