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From: jeffrey@sci.ccny.cuny.edu (Jeffrey L Bromberger)
Newsgroups: comp.sys.3b1
Subject: Re: Paranoia freaks under SVS Fortran!
Keywords: SERIOUS DEFECTS
Message-ID: <1991Mar3.013043.7243@sci.ccny.cuny.edu>
Date: 3 Mar 91 01:30:43 GMT
References: <1991Mar1.194517.10627@notvax.ccny.cuny.edu> <1991Mar1.203900.11034@notvax.ccny.cuny.edu> <1991Mar2.014748.23501@athena.mit.edu>
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Organization: City College of New York - Science Computing Facility
Lines: 38

In article <1991Mar2.014748.23501@athena.mit.edu> pschmidt@athena.mit.edu (Peter H. Schmidt) writes:
>In article <1991Mar1.203900.11034@notvax.ccny.cuny.edu> jeffrey@sci.ccny.cuny.edu (Jeffrey Bromberger) writes:
>>> The arithmetic diagnosed has unacceptable Serious Defects.
>Paranoia hasn't been around on Unix machines for more than a couple years, and
>vendor awareness of the importance of conforming to the IEEE floating point
>spec (for Unix machines) only really struck with the advent of workstations.

Well, I don't know about that. Our old 11/780 (while it *is* much
bigger, but slower in CPU stuff) does this stuff reasonable well.
Some of our 68K based machines also do it well.  And they are from
before the 3b1.   After seeing those errors, I wonder how my old
VIC-20 would do with them!

>The graphics involve mucho floating point, and the flaw in your roundoff
>routines becomes real apparent when your X-windows "ico" starts to look more
>like a crumpled paper towel (I actually had to use this as a demo to convince
>one of our more recalcitrant developers ;-).

So much for porting over a generic graphics library - I cannot ever
hope to explain to my thesis committee why that nice smooth surface
resembles a crumpled paper towel :-)

>The good news is that the flaws mentioned won't affect most of the work a 3b1
>is best suited for.  After all, it isn't exactly a FLOPS power house.

Power house or not, there are folk trying to run SPICE on this thing.
That is what prompted Jim Adams (from U of Cincinnati) to fix the
floating point stuff.  BTW: even after fixing the libraries, nothing
improved.  Not a single thing.  How's that for a bummer!

Anybody out there good in writing math libraries? (asbestos donned)

j
-- 
Jeffrey L. Bromberger
System Operator---City College of New York---Science Computing Facility
jeffrey@sci.ccny.cuny.edu			jeffrey@ccnysci.BITNET
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