ldexp(3)


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 4.09 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                          LDEXP(3)





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