NAME

       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl - compute exponent 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  normally 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 implementation-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 historical definition of the scalb()
       function from the Single UNIX Specification.  The difference is that the scalb() function  has  a  second
       argument  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 provided because the factor required to scale from  the  smallest
       positive  floating-point  value  to  the  largest  finite  one,  on many implementations, 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 .