'\" t
.\" @(#)feclearexcept.3m 1.5 00/01/01 SMI
.TH feclearexcept 3M  "01/01/00"
.SH NAME
feclearexcept, feraiseexcept, fetestexcept, fegetexceptflag,
fesetexceptflag \- access floating point exception flags
.SH SYNOPSIS
.LP
.B cc
.RI "[ " "flag" " \|.\|.\|. ] " "file" " \|.\|.\|."
.B -R/opt/SUNWspro/lib -L/opt/SUNWspro/lib -lm9x
.RI "[ " "library" " \|.\|.\|. ]"
.LP
.B #include <fenv.h>
.LP
.BI "void feclearexcept(int " excepts );
.LP
.BI "void feraiseexcept(int " excepts );
.LP
.BI "int fetestexcept(int " excepts );
.LP
.BI "void fegetexceptflag(fexcept_t *" flagp ", int " excepts );
.LP
.BI "void fesetexceptflag(const fexcept_t *" flagp ", int " excepts );
.LP
.SH DESCRIPTION
.IX "feclearexcept function" "" "\fLfeclearexcept()\fP function"
.IX "feraiseexcept function" "" "\fLferaiseexcept()\fP function"
.IX "fetestexcept function" "" "\fLfetestexcept()\fP function"
.IX "fegetexceptflag function" "" "\fLfegetexceptflag()\fP function"
.IX "fesetexceptflag function" "" "\fLfesetexceptflag()\fP function"
.LP
These functions provide access to the floating point exception flags.  For
each function, the \f2excepts\f1 argument specifies one or more exceptions
indicated by a bitwise "or" of any of the following values (defined in
\f3<fenv.h>\f1):
.LP
.RS
.PD 0
.TP 20
\s-1FE_INEXACT\s0
.TP
\s-1FE_UNDERFLOW\s0
.TP
\s-1FE_OVERFLOW\s0
.TP
\s-1FE_DIVBYZERO\s0
.TP
\s-1FE_INVALID\s0
.PD
.RE
.LP
For convenience, the macro \s-1FE_ALL_EXCEPT\s0 is defined to be the bitwise
"or" of all of the above values.
.LP
\f3feclearexcept(\f2excepts\f3)\f1 clears the flags for the specified
exceptions.
.LP
\f3feraiseexcept(\f2excepts\f3)\f1 raises the specified exceptions: for each
exception indicated, if \s-1FEX_NONSTOP\s0 handling mode is in effect, the
exception's flag is set, and otherwise the appropriate action is taken as
described in \f3fex_set_handling\f1(3M).
.LP
\f3fetestexcept(\f2excepts\f3)\f1 returns a bitwise "or" of the values
listed above corresponding to the subset of the specified exceptions whose
flags are set.
.LP
\f3fegetexceptflag(\f2flagp\f3, \f2excepts\f3)\f1 saves the current values of
the flags for the exceptions indicated by \f2excepts\f1 in the object pointed
to by \f2flagp\f1.  The type \f3fexcept_t\f1 is defined in \f3<fenv.h>\f1.
.LP
\f3fesetexceptflag(\f2flagp\f3, \f2excepts\f3)\f1 restores the values of the
flags for the exceptions indicated by \f2excepts\f1 from the object pointed
to by \f2flagp\f1.  This object must have been set by a previous call to
\f3fegetexceptflag(\|)\f1; otherwise the effect on the indicated flags is
undefined.  (The \f3fesetexceptflag\f1 function does not raise exceptions,
but only sets the state of the flags.)
.SH EXAMPLE
The following code fragment calls the function \f3f(\|)\f1 if the invalid
operation flag is set and \f3g(\|)\f1 if the overflow flag is set:
.LP
.RS
.nf
.vs 11p
.ft B
.ne 12
#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();
	/*...*/
}
.vs
.fi
.RE
.LP
.SH ATTRIBUTES
See
.BR attributes (5)
for descriptions of the following attributes:
.sp
.ne 10
.TS
box;
cbp-1 | cbp-1
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
=
Availability	SPROm9xs
Interface Stability	Standard
MT-Level	MT-Safe
.TE
.SH "SEE ALSO"
.BR fegetenv (3M),
.BR fex_set_handling (3M),
.BR fex_set_log (3M),
.BR attributes (5)
.LP
.I Numerical Computation Guide
.SH NOTES
When the \s-1FEX_CUSTOM\s0 handling mode is in effect for an exception, raising
that exception via \f3feraiseexcept\f1 will cause the handling function to be
invoked.  The handling function may then modify the exception flags to be set
as described in \f3fex_set_handling\f1(3M).  Any result value the handler
supplies will be ignored.
.LP
As shown in the synopsis, the recommended way to link with libm9x using
\f3cc\f1 is to specify
.LP
.RS
.BI -R install-path "/lib -L" install-path "/lib -lm9x"
.RE
.LP
on the command line, where \f2install-path\f1 refers to the location in
which the compilers are installed (/opt/SUNWspro by default).  See the
\f2Numerical Computation Guide\f1 for additional information about linking
with libm9x.