trpfpe.3f

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3F 代码 · 共 66 行

.\" SCCSID: @(#)trpfpe.3f	8.1	9/11/90
.\" michaud jan 9, l987; took range.3f out of see also
.\" until a manpage is written for it.
.TH trpfpe 3f VAX "" Unsupported
.SH Name
trpfpe, fpecnt \- trap and repair floating point faults
.SH Syntax
.B subroutine trpfpe (numesg, rtnval)
.br
.B double precision rtnval
.sp 1
.B integer function fpecnt ()
.sp 1
.B common /fpeflt/ fperr
.br
.B logical fperr
.SH Description
.NXR "trpfpe subroutine (FORTRAN)"
.NXR "fpecnt subroutine (FORTRAN)"
.NXR "floating point arithmetic" "trapping overflow"
The
.PN trpfpe
routine sets up a signal handler to trap arithmetic exceptions.
If the exception is due to a floating point arithmetic fault,
the result of the operation is replaced with the
.I rtnval
specified.
The
.I rtnval
must be a double precision value. For example, ``0d0'' or ``dflmax()''.
.PP
The first
.I numesg
occurrences of a floating point arithmetic error will cause a message
to be written to the standard error file.
Any exception that cannot be repaired will result in the default
action, typically an abort with core image.
.PP
The
.PN fpecnt
routine
returns the number of faults since the last call to
.PN trpfpe .
.PP
The logical value in the common block labeled
.I fpeflt
will be set to .true.  each time a fault occurs.
.SH Restrictions
This routine works only for
.IR faults ,
not
.IR traps .
This is primarily due to the VAX architecture.
.PP
If the operation involves changing the stack pointer, it cannot be repaired.
This seldom should be a problem with the f77 compiler, but such an operation
might be produced by the optimizer.
.PP
The POLY and EMOD opcodes are not dealt with.
.SH Files
.ie \nM /usr/ucb/lib/libF77.a
.el /usr/lib/libF77.a
.SH See Also
signal(3f) 
.\" range(3f)