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feclearexcept(3)

NAME

     feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag,
     fetestexcept -- floating-point exception flag manipulation

LIBRARY

     Math Library (libm, -lm)

SYNOPSIS

     #include <fenv.h>
     #pragma STDC FENV_ACCESS ON

     int
     feclearexcept(int excepts);

     int
     fegetexceptflag(fexcept_t *flagp, int excepts);

     int
     feraiseexcept(int excepts);

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

     int
     fetestexcept(int excepts);

DESCRIPTION

     The feclearexcept() routine clears the floating-point exception flags
     specified by excepts, whereas feraiseexcept() raises the specified excep-
     tions.  Raising an exception causes the corresponding flag to be set, and
     a SIGFPE is delivered to the process if the exception is unmasked.

     The fetestexcept() function determines which flags are currently set, of
     those specified by excepts.

     The fegetexceptflag() function stores the state of the exception flags
     specified in excepts in the opaque object pointed to by flagp.  Simi-
     larly, fesetexceptflag() changes the specified exception flags to reflect
     the state stored in the object pointed to by flagp.  Note that the flags
     restored with fesetexceptflag() must be a (not necessarily proper) subset
     of the flags recorded by a prior call to fegetexceptflag().

     For all of these functions, the possible types of exceptions include
     those described in fenv(3).  Some architectures may define other types of
     floating-point exceptions.

IMPLEMENTATION NOTES

     On some architectures, raising an overflow or underflow exception also
     causes an inexact exception to be raised.	In these cases, the overflow
     or underflow will be raised first.

     The fegetexceptflag() and fesetexceptflag() routines are preferred to
     fetestexcept() and feraiseexcept(), respectively, for saving and restor-
     ing exception flags.  The latter do not re-raise exceptions and may pre-
     serve architecture-specific information such as addresses where excep-
     tions occurred.

     fpresetsticky(3)

STANDARDS

     The feclearexcept(), fegetexceptflag(), feraiseexcept(),
     fesetexceptflag(), and fetestexcept() routines conform to ISO/IEC
     9899:1999 (``ISO C99'').

HISTORY

     These functions first appeared in FreeBSD 5.3.

FreeBSD 5.4			  May 8, 2004			   FreeBSD 5.4

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