From: utzoo!henry
Newsgroups: net.micro.68k
Title: Re: 68K vs 286 on floats 
Article-I.D.: utzoo.2839
Posted: Mon Feb 28 17:01:27 1983
Received: Mon Feb 28 17:01:27 1983

No offense to John Gilmore and the other folks at Sun, but comparing
Sun's 32-bit software floating point to the IEEE-standard 8087/80287 is
really comparing a Piper Cub to a Concorde.  What are the error bounds
of the Sun package?  What is its roundoff algorithm, and why?  Under what
circumstances is it unsafe to use?  (Alas, considering my past experience
with software floating-point packages, a better question would probably
be "under what circumstances is it safe to use?".)  I don't doubt that
the folks who did it were competent -- certainly the Sun people that I
know are pretty good -- but designing floating-point arithmetic algorithms
is a job for a numerical-mathematics expert, not a systems programmer.
It really is too big and too hard a job for an amateur to do well.  If
somebody like (say) Kahan was numerical-mathematics consultant to the
project, and is satisfied with the result, then I'd be happy to use it.
Otherwise, I wouldn't trust the numbers coming out.  Sorry.

Actually, what I would like to see is a decent 68000 or 16032 system
(the Sun is reasonable) with an 80[2]87 on it for floating-point work.
The promised 68000 and 16032 floating-point auxiliaries are useful
things, but they don't have quite the same awe-inspiring capabilities
and specs as the Intel chips.  A lot of people have cursed the 8087
for being impossible to interface to anything but an 8086;  by the
sounds of things, the 80287 may be easier to deal with.

					Henry Spencer
					U of Toronto