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I doubt this is a new issue. The underlying arithmetic is IEEE 754.<br>
Floating point numbers have the following problems (at least):<br>
<br>
- addition is not associative<br>
- not all decimal numbers within the range of representable numbers
are representable exactly<br>
<br>
Basically, it is rarely justifiable to test for equality of doubles.<br>
<br>
Edward<br>
<br>
<br>
<div class="moz-cite-prefix">On 3/4/14 11:21 AM, Matt Jones wrote:<br>
</div>
<blockquote
cite="mid:CAFSW8x=nNPjuXsftGO9BDUWcWpCwCm0fzxhJjpW9Uf2r_YGX1Q@mail.gmail.com"
type="cite">
<div dir="ltr">Daniel and Christopher --
<div><br>
</div>
<div>Do either of you have any insight into this new rounding
issue? Can you confirm whether or not this is new behavior?</div>
<div><br>
</div>
<div>Matt<br>
<br>
<div class="gmail_quote">
---------- Forwarded message ----------<br>
From: <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:noreply@nceas.ucsb.edu">noreply@nceas.ucsb.edu</a>></span><br>
Date: Tue, Mar 4, 2014 at 3:24 AM<br>
Subject: [Kepler - Bug #6439] (New) Double rounding fails in
some cases while evaluating Expressions<br>
To: <br>
<br>
<br>
<div>
<span></span>
Issue #6439 has been reported by Owsiak Michal.
<hr>
<h1><a moz-do-not-send="true"
href="https://projects.ecoinformatics.org/ecoinfo/issues/6439"
target="_blank">Bug #6439: Double rounding fails in
some cases while evaluating Expressions</a></h1>
<ul>
<li>Author: Owsiak Michal</li>
<li>Status: New</li>
<li>Priority: Urgent</li>
<li>Assignee: Derik Barseghian</li>
<li>Category: actors</li>
<li>Target version: 2.3.0</li>
<li>Bugzilla-Id: </li>
</ul>
<p>It seems that addition of doubles can produce values
slightly different than they should to be.</p>
<p>Please take a look at attached workflow
(simple_error.xml).</p>
<p>Condition that should be satisfied to escape the loop
is: 1.7 > 1.5 + 0.1</p>
<p>However, loop is interrupted sooner, because of
incorrect calculation of doubles. Value of "p" is set
to: 1.6000000000000003</p>
<p>This, of course, makes it impossible to use doubles as
check points for the loops.</p>
<p>However, it seems that casting to string and back works
fine (take a look at second workflow - simple.xml)</p>
<p>Cheers</p>
<p>Michal</p>
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