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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; 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, an  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 func-
       tions.

       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.

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 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                  2008-08-05                          LDEXP(3)