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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 (consult 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  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 .

IEEE/The Open Group                  2003                            SCALB(3P)