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

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

SYNOPSIS
       #include 

       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 featuretestmacros(7)):

       ldexpf(), ldexpl():
           BSDSOURCE || SVIDSOURCE || XOPENSOURCE >= 600 ||
           ISOC99SOURCE || POSIXCSOURCE >= 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
       HUGEVAL, HUGEVALF, or HUGEVALL, respectively, with a sign  the  same
       as x.

ERRORS
       See  matherror(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
              (FEOVERFLOW) is raised.

       Range error, underflow
              errno  is  set to ERANGE.  An underflow floating-point exception
              (FEUNDERFLOW) 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.  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)