Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


LDEXP(3) Linux Programmer's Manual LDEXP(3)


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


     #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


     These functions return the result  of  multiplying  the  floating-point
     number x by 2 raised to the power exp.


     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 (nega-
     tive 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.


     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.


     For   an   explanation   of   the  terms  used  in  this  section,  see
     allbox; lbw27 lb lb  l  l  l.   Interface Attribute Value  T{  ldexp(),
     ldexpf(), ldexpl() T}   Thread safety  MT-Safe


     C99, POSIX.1-2001, POSIX.1-2008.
     The variant returning double also conforms to SVr4, 4.3BSD, C89.


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


     This  page  is  part of release 4.16 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
                                2017-09-15                          LDEXP(3)
/data/webs/external/dokuwiki/data/pages/man/ldexpf.txt · Last modified: 2019/05/17 09:32 by

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki