huschi.net

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

                                  2010-09-20                          LDEXP(3)