LDEXP(3)                            Linux Programmer's Manual                            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():
           _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, 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
   Multithreading (see pthreads(7))
       The ldexp(), ldexpf(), and ldexpl() functions are thread-safe.

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 3.74 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 http://www.kernel.org/doc/man-pages/.



                                            2013-08-19                                   LDEXP(3)