Man Page fesetexceptflag.3m

NAME

     feclearexcept, feraiseexcept, fetestexcept, fegetexceptflag,
     fesetexceptflag - access floating point exception flags

SYNOPSIS

     cc   [   flag   ...   ]   file   ...     -R/opt/SUNWspro/lib
     -L/opt/SUNWspro/lib -lm9x [ library ... ]

     #include <fenv.h>

     void feclearexcept(int excepts);

     void feraiseexcept(int excepts);

     int fetestexcept(int excepts);

     void fegetexceptflag(fexcept_t *flagp, int excepts);

     void fesetexceptflag(const fexcept_t *flagp, int excepts);

DESCRIPTION

     These functions provide access to the floating point  excep-
     tion  flags.  For each function, the excepts argument speci-
     fies one or more exceptions indicated by a bitwise  "or"  of
     any of the following values (defined in <fenv.h>):

          FE_INEXACT
          FE_UNDERFLOW
          FE_OVERFLOW
          FE_DIVBYZERO
          FE_INVALID

     For convenience, the macro FE_ALL_EXCEPT is  defined  to  be
     the bitwise "or" of all of the above values.

     feclearexcept(excepts) clears the flags  for  the  specified
     exceptions.

     feraiseexcept(excepts) raises the specified exceptions:  for
     each exception indicated, if FEX_NONSTOP handling mode is in
     effect, the exception's  flag  is  set,  and  otherwise  the
     appropriate    action    is    taken    as    described   in
     fex_set_handling(3M).

     fetestexcept(excepts) returns a bitwise "or" of  the  values
     listed  above  corresponding  to the subset of the specified
     exceptions whose flags are set.

     fegetexceptflag(flagp, excepts) saves the current values  of
     the  flags  for  the  exceptions indicated by excepts in the
     object pointed to by flagp.  The type fexcept_t  is  defined
     in <fenv.h>.
     fesetexceptflag(flagp, excepts) restores the values  of  the
     flags  for  the  exceptions  indicated  by  excepts from the
     object pointed to by flagp.  This object must have been  set
     by  a  previous  call  to  fegetexceptflag();  otherwise the
     effect on the indicated flags is undefined.   (The  fesetex-
     ceptflag  function  does not raise exceptions, but only sets
     the state of the flags.)

EXAMPLE

     The following code fragment calls the function  f()  if  the
     invalid  operation  flag is set and g() if the overflow flag
     is set:

          #include <fenv.h>
          /*...*/
          {
               int set_excepts;

               feclearexcept(FE_INVALID | FE_OVERFLOW);
               /* computation that may raise exceptions */
               set_excepts = fetestexcept(FE_INVALID | FE_OVERFLOW);
               if (set_excepts & FE_INVALID) f();
               if (set_excepts & FE_OVERFLOW) g();
               /*...*/
          }

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     _______________________________________
    |   ATTRIBUTE TYPE   |  ATTRIBUTE VALUE|
    |____________________|__________________|_
    | Availability       |  SPROm9xs       |
    | Interface Stability|  Standard       |
    | MT-Level           |  MT-Safe        |
    |____________________|_________________|

     fegetenv(3M), fex_set_handling(3M), fex_set_log(3M),  attri-
     butes(5)

     Numerical Computation Guide

     When the FEX_CUSTOM handling mode is in effect for an excep-
     tion,  raising  that  exception via feraiseexcept will cause
     the handling function to be invoked.  The handling  function
     may  then  modify the exception flags to be set as described
     in fex_set_handling(3M).  Any result value the handler  sup-
     plies will be ignored.

     As shown in the synopsis, the recommended way to  link  with
     libm9x using cc is to specify

          -Rinstall-path/lib -Linstall-path/lib -lm9x

     on the command line, where install-path refers to the  loca-
     tion  in which the compilers are installed (/opt/SUNWspro by
     default).  See the Numerical  Computation  Guide  for  addi-
     tional information about linking with libm9x.