Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!decwrl!asylum!osc!jgk From: jgk@osc.COM (Joe Keane) Newsgroups: comp.arch Subject: Re: Killer Micro II Keywords: floating point Message-ID: <3755@osc.COM> Date: 5 Sep 90 07:11:35 GMT References: <527@llnl.LLNL.GOV> <603@array.UUCP> <2482@l.cc.purdue.edu> <2497@l.cc.purdue.edu> Reply-To: jgk@osc.COM (Joe Keane) Organization: Versant Object Technology, Menlo Park, CA Lines: 28 I have to agree that 128-bit floating point isn't really such a hot idea. When you get right down to it, floating point is a hack. It's a very useful hack; i won't argue with that. We admit 64-bit floating point doesn't work, so what do we do? We provide more of the same. Of course this is the conservative thing to do, so i bet we'll see some big company come out with 128-bit floating point soon. I don't care if you have 65536-bit floating point, it's still floating point. That means underflow, overflow, round-off error, loss of precision, need i continue? Not to mention that it's now slug slow from all those bits. You can push the problems back but they don't go away. There are a lot of machines out there that can do IEEE 64-bit floating point, with all its precise rules and cases, but can't multiply two 32-bit integers in a reasonable way. What are we to make of this? It's just dumb. The silicon is there, but there's no perceived demand for that feature. I'd be so happy to see reasonable support for multiple-precision integers in most machines. Our current programming languages have a strong influence. C has `float' and `double' types, and most machines have single-precision and double-precision floating point numbers. Coincidence? I think not. Another interesting area is hardware support for arbitrary-precision real numbers. Of course that brings up the dreaded word `closure', at which point most C programmers throw up their hands. Some day i'll write a nifty tech report about it. Then maybe i can bribe a hardware guy to add a couple instructions to some math co-processor. Yeah right.