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 integer 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 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

       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, 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 .