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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: floating point comparison
Date: 1997/08/06
Message-ID: <dewar.870870231@merv>#1/1
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References: <mheaney-ya023680002907972345420001@news.ni.net>
 <33DF6F43.6EEA4806@digicomp.com> <5rqehs$g1r$1@odin.cc.pdx.edu>
 <33E11967.4A30@nr.net> <33E214C3.311C@pseserv3.fw.hac.com>
 <dewar.870525385@merv> <33E61497.33E2@pseserv3.fw.hac.com>
Organization: New York University
Newsgroups: 
 comp.lang.ada,sci.math.num-analysis,comp.software-eng,comp.theory,sci.math
Date: 1997-08-06T00:00:00+00:00
List-Id: <comp.lang.ada>


Wes said:

<<I understand floating point well enough to compute with pencil &
paper the correct bit pattern for Pi (3.14159.....) in a VAX
D_FLOAT, but I have never seen IEEE 754.  Yet I almost always>>

Hmmm! I hardly call a few digits of a decimal approximation a "bit
pattern". In fact computing the properly rounded binary approximation
to pi in Vax D_FLoat is not trivial at all, but we can clearly seee
the thinking here.

Look my number is about pi, since the decimal conversion looks right,
therefore the bit pattern must be correct.

Nope! Sorry, this simply is not a correct conclusion!