Man Linux: Main Page and Category List

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 .