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SCALBLN(3P)                POSIX Programmer's Manual               SCALBLN(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl -  compute  expo-
       nent using FLT_RADIX
SYNOPSIS
       #include <math.h>
       double scalbln(double x, long n);
       float scalblnf(float x, long n);
       long double scalblnl(long double x, long n);
       double scalbn(double x, int n);
       float scalbnf(float x, int n);
       long double scalbnl(long double x, int n);

DESCRIPTION
       These  functions  shall  compute x * FLT_RADIX**n efficiently, not nor-
       mally by computing FLT_RADIX**n explicitly.
       An application wishing to check for error situations should  set  errno
       to  zero  and  call  feclearexcept(FE_ALL_EXCEPT)  before calling these
       functions.  On return, if errno is non-zero or  fetestexcept(FE_INVALID
       |  FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
       occurred.
RETURN VALUE
       Upon   successful   completion,   these    functions    shall    return
       x * FLT_RADIX**n.
       If the result would cause overflow, a range error shall occur and these
       functions  shall  return  +-HUGE_VAL,  +-HUGE_VALF,   and   +-HUGE_VALL
       (according  to the sign of x) as appropriate for the return type of the
       function.
       If the correct value would cause underflow, and is not representable, a
       range  error may occur, and  either 0.0 (if supported), or an implemen-
       tation-defined value shall be returned.
       If x is NaN, a NaN shall be returned.
       If x is +-0 or +-Inf, x shall be returned.
       If n is 0, x shall be returned.
       If the correct value would cause underflow,  and  is  representable,  a
       range error may occur and the correct value shall be returned.
ERRORS
       These functions shall fail if:
       Range Error
              The result overflows.
       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then the overflow
       floating-point exception shall be raised.

       These functions may fail if:
       Range Error
              The result underflows.
       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
       then  errno  shall  be  set  to  [ERANGE].  If  the  integer expression
       (math_errhandling & MATH_ERREXCEPT) is  non-zero,  then  the  underflow
       floating-point exception shall be raised.

       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       On   error,   the   expressions  (math_errhandling  &  MATH_ERRNO)  and
       (math_errhandling & MATH_ERREXCEPT) are independent of each other,  but
       at least one of them must be non-zero.
RATIONALE
       These  functions are named so as to avoid conflicting with the histori-
       cal definition of the scalb() function from the Single UNIX  Specifica-
       tion.   The  difference is that the scalb() function has a second argu-
       ment of double instead of int. The scalb() function is not part of  the
       ISO C  standard. The three functions whose second type is long are pro-
       vided because the factor required to scale from the  smallest  positive
       floating-point  value  to  the  largest finite one, on many implementa-
       tions, is too large to represent in the minimum-width int format.
FUTURE DIRECTIONS
       None.
SEE ALSO
       feclearexcept(), fetestexcept(), scalb(), the Base  Definitions  volume
       of  IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error Conditions
       for Mathematical Functions, <math.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                          SCALBLN(3P)