[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
- To: dlw at SCRC-TENEX at MIT-MC
- Subject: Re: x^0.0
- From: HEDRICK at RUTGERS (Mgr DEC-20s/Dir LCSR Comp Facility)
- Date: Wed, 01 Dec 1982 22:10:00 -0000
- Cc: Kim.fateman at UCB-C70, common-lisp at SU-AI
- In-reply-to: Your message of 1-Dec-82 1706-EST
I would like for any computation that doesn't have a well-defined value
to be either an error or result in some item which can never turn into a
normal number, even after being multiplied by 0.0. The problem with
things like +UNDEFINED is that when you multiply them by 0.0, you get
0.0. But depending upon the exact expression involved and how you take
the limit, that is not necessarily a good result. The problem with
+UNDEFINED or +INF is that you have only choices, neither of them very
- make them contagious. Any computation involving one of them
produces a result that is either UNDEFINED or INF. The problem
there is that you can do an hour-long computation that
returns UNDEFINED, and have no idea where the error occured.
- make 0 * UNDEFINED = 0. But that can result in meaningless answers.
It seems that you you supply, at least as an option, the ability to
generate an error whenever something questionable is happening.