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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: floating point comparison
Date: 1997/08/09
Message-ID: <dewar.871099446@merv>#1/1
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Organization: New York University
Newsgroups: 
 comp.lang.ada,sci.math.num-analysis,comp.software-eng,comp.theory,sci.math
Date: 1997-08-09T00:00:00+00:00
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Gerhard says

<<Maybe it should be clarified WHY one would want to test for equality.
I can imagine two distinct situations:
>>

There are many other situations besides those that you mentioned, the
following immediately come to mind:

  1. A test for zero may be quite reasonable, even with signed zeroes,
     and infinities, the case of zero may require special handling
     which is not required for small non-zero values.

  2. Careful analysis may show that an iterative algorithm converges
     to precise equality under the roudning regime being used. In such
     a case, it may be both more accurate and more efficient to check
     for precise convergence.

  3. If you know that the values that are represented are all precisely
     represented (e.g. integersin a representable range), then exact
     equality is perfectly reasonable.

  4. Precise equality comparisons with infinity are often perfectly
     appropriate (and indeed the idea of epsilon testing here is
     completely bogus)

Plus many more ...