Path: utzoo!attcan!uunet!lll-winken!lll-lcc!lll-tis!helios.ee.lbl.gov!nosc!ucsd!ames!lamaster
From: lamaster@ames.arc.nasa.gov (Hugh LaMaster)
Newsgroups: comp.arch
Subject: Re: Standard Un*x H/W architecture
Message-ID: <12055@ames.arc.nasa.gov>
Date: 20 Jul 88 13:33:49 GMT
References: <980@garth.UUCP> <76700037@p.cs.uiuc.edu> <12005@ames.arc.nasa.gov> <10298@lll-winken.llnl.gov>
Reply-To: lamaster@ames.arc.nasa.gov.UUCP (Hugh LaMaster)
Organization: NASA Ames Research Center, Moffett Field, Calif.
Lines: 18

In article <10298@lll-winken.llnl.gov> brooks@maddog.UUCP (Eugene D. Brooks III) writes:
>fixing the code.  Any machine with IEEE arithmetic outght to have
>a "round inward an extra couple of bits" option for "ragged edge"
>detection.  If it happens to result in 10% faster execution time

Excellent point.  I agree.  One of the nice features of the Cray CFT
Fortran compiler is a compiler switch which generates an extra
truncation instruction with each assignment.  You can truncate to the
desired number of bits and see just how sensitive your code is to small
truncation errors.  I wish every compiler had such a switch.  It is nice,
however, to be able to turn it off :-)



-- 
  Hugh LaMaster, m/s 233-9,  UUCP ames!lamaster
  NASA Ames Research Center  ARPA lamaster@ames.arc.nasa.gov
  Moffett Field, CA 94035     
  Phone:  (415)694-6117