Re: IEEE floating point

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#11889

From: Don Wells
Date: Thu, 30 May 1991 21:39

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In article <MCCALPIN.91May30105154@pereland.cms.udel.edu>
mccalpin@perelandra.cms.udel.edu (John D. McCalpin) writes:

   ...  The IBM
   HEX results are only 2-3 bits worse than IEEE, which is seldom
   disastrous.  If this 2-3 bit difference does cause your application
   serious trouble, then you should be running at the next higher
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   precision on all the platforms....
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I disagree with this statement.

The 2-3 bit difference is very nearly one whole decimal digit.  You
need at least one digit for truncation guard (two is better), and you
want to resolve the noise (about one more digit), so if your dynamic
range is 4 digits (and quite a few measurement systems are this good
today), you generally have just enough digits for signal processing
with IEEE, but quite possibly not enough with hex normalization.

--

Donald C. Wells             Associate Scientist        dwells@nrao.edu
National Radio Astronomy Observatory                   +1-804-296-0277
Edgemont Road                                     Fax= +1-804-296-0278
Charlottesville, Virginia 22903-2475 USA            78:31.1W, 38:02.2N

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From: dwells@fits.cx.nrao.edu (Don Wells)
Newsgroups: comp.arch
Subject: Re: IEEE floating point
Message-ID: <DWELLS.91May30163907@fits.cx.nrao.edu>
Date: 30 May 91 21:39:07 GMT
References: <9105250030.AA08036@ucbvax.Berkeley.EDU>
 <1991May25.222551.16365@zoo.toronto.edu>
 <MCCALPIN.91May26100257@pereland.cms.udel.edu>
 <MCCALPIN.91May27092950@pereland.cms.udel.edu>
 <MCCALPIN.91May29164641@pereland.cms.udel.edu>
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In-Reply-To: mccalpin@perelandra.cms.udel.edu's message of 30 May 91 14: 51:54 GMT

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