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 .