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<p>I'm interested in knowing how the differences arise. I can understand how different machines, compilers can give numerical results that differ at the limits of the selected precision, but it's not obvious how this leads to the generation of different meshes.</p>
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<p>Gib<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> gmsh <gmsh-bounces@ace20.montefiore.ulg.ac.be> on behalf of moritz braun <moritz.braun@gmail.com><br>
<b>Sent:</b> Monday, 1 July 2019 10:28 p.m.<br>
<b>To:</b> Christophe Geuzaine<br>
<b>Cc:</b> gmsh@onelab.info; gmsh@geuz.org<br>
<b>Subject:</b> [FORGED] Re: [Gmsh] Windows, Ubuntu give different meshes</font>
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<div>Dear Christophe</div>
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<div>I assume identical geometries leading to different meshes</div>
<div>between different versions of redhat 7.4 to 7.6 <br>
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<div>can be expected. <br>
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<div>I was quite surprised because my self consitent code behaved differently depending</div>
<div>on the redhat version and now I understand!</div>
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<div>Regards</div>
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<div>Moritz <br>
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<div dir="ltr" class="gmail_attr">On Fri, Jun 28, 2019 at 8:04 AM Christophe Geuzaine <<a href="mailto:cgeuzaine@uliege.be">cgeuzaine@uliege.be</a>> wrote:<br>
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<br>
<br>
> On 27 Jun 2019, at 03:33, Gib Bogle <<a href="mailto:g.bogle@auckland.ac.nz" target="_blank">g.bogle@auckland.ac.nz</a>> wrote:<br>
> <br>
> I have been testing with the demo file cube.geo:<br>
> <br>
> lc = 0.3;<br>
> Point(1) = {0.0,0.0,0.0,lc};<br>
> Point(2) = {1,0.0,0.0,lc};<br>
> Point(3) = {1,1,0.0,lc};<br>
> Point(4) = {0,1,0.0,lc};<br>
> Line(1) = {4,3};<br>
> Line(2) = {3,2};<br>
> Line(3) = {2,1};<br>
> Line(4) = {1,4};<br>
> Line Loop(5) = {2,3,4,1};<br>
> Plane Surface(6) = {5};<br>
> tmp[] = Extrude {0,0.0,1} {<br>
> Surface{6};<br>
> };<br>
> Physical Volume(1) = tmp[1];<br>
> <br>
> I generate the mesh file at the command line like this:<br>
> <br>
> gmsh -3 cube.geo<br>
> <br>
> on a Windows 7 machine and on Ubuntu 16.04. The gmsh version is 4.3.0.<br>
> <br>
> I find that the meshes created on the two systems are a bit different. On Windows the mesh has 137 nodes and 372 elements, while on Ubuntu it has 136 nodes and 373 elements.<br>
> <br>
> Should I be concerned about this?<br>
<br>
No, on the same machine the meshes should be identical, but across OSes (and different compilers) small variations are normal.<br>
<br>
Christophe<br>
<br>
<br>
> <br>
> Thanks<br>
> Gib<br>
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<br>
— <br>
Prof. Christophe Geuzaine<br>
University of Liege, Electrical Engineering and Computer Science <br>
<a href="http://www.montefiore.ulg.ac.be/~geuzaine" rel="noreferrer" target="_blank">http://www.montefiore.ulg.ac.be/~geuzaine</a><br>
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-- <br>
<div dir="ltr" class="gmail_signature">Prof M Braun Tel.:27-12-4298006/8027<br>
Physics Department Fax.: 27-12-4293643<br>
University of South Africa (UNISA) <br>
<a href="mailto:moritz.braun@gmail.com" target="_blank">moritz.braun@gmail.com</a><br>
P.O. Box 392 <br>
0003 <br>
UNISA<br>
South Africa <br>
<a href="http://moritz-braun.blogspot.com" target="_blank">http://moritz-braun.blogspot.com</a><br>
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