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



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       scalb - load exponent of a radix-independent floating-point number

SYNOPSIS
       #include <math.h>

       double scalb(double x, double n);


DESCRIPTION
       The  scalb() function shall compute x*r**n, where r is the radix of the machine's floating-point arithmetic. When r is 2,
       scalb() shall be equivalent to ldexp(). The value of r is FLT_RADIX which is defined in <float.h>.

       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, the scalb() function shall return x*r**n.

       If x or n is NaN, a NaN shall be returned.

       If n is zero, x shall be returned.

       If x is +-Inf and n is not -Inf, x shall be returned.

       If x is +-0 and n is not +Inf, x shall be returned.

       If x is +-0 and n is +Inf, a domain error shall occur, and either a NaN  (if  supported),  or  an  implementation-defined
       value shall be returned.

       If  x  is  +-Inf and n is -Inf, a domain error shall occur, and either a NaN (if supported), or an implementation-defined
       value shall be returned.

       If the result would cause an overflow, a range error shall occur and +-HUGE_VAL (according to the sign  of  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.

       If the correct value would cause underflow, and is not representable, a range error may occur, and 0.0 shall be returned.

ERRORS
       The scalb() function shall fail if:

       Domain Error
              If x is zero and n is +Inf, or x is Inf and n is -Inf.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the  integer
       expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.

       Range Error
              The result would overflow.

       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the inte-
       ger expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then  the  overflow  floating-point  exception  shall  be
       raised.


       The scalb() function 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 inte-
       ger 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
       Applications should use either scalbln(), scalblnf(), or scalblnl() in preference to this function.

       IEEE Std 1003.1-2001 only defines the behavior for the scalb() function when the n argument is an integer, a NaN, or Inf.
       The behavior of other values for the n argument is unspecified.

       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
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       feclearexcept(),    fetestexcept(),   ilogb(),   ldexp(),   logb(),   scalbln(),   the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for Mathematical Functions, <float.h>, <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, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                     SCALB(3P)