[Gmsh] Setting random seed in geo file
David Bernstein
David.Bernstein at meliorinnovations.com
Tue Dec 9 19:43:23 CET 2014
Hi Serban, Thanks for looking into this!
Dave
On Dec 9, 2014, at 8:32 AM, Serban Georgescu <Serban.Georgescu at uk.fujitsu.com<mailto:Serban.Georgescu at uk.fujitsu.com>> wrote:
For reference, an update to the modifications below.
MVertexLessThanNum should be used instead if MVertexLessThanLexicographic.
For some reason that I do not understand, MVertexLessThanLexicographic leads to crashes in some cases.
Serban
From: gmsh [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be] On Behalf Of Serban Georgescu
Sent: 05 December 2014 12:40
To: David Bernstein
Cc: gmsh at geuz.org<mailto:gmsh at geuz.org> Geuzaine
Subject: Re: [Gmsh] Setting random seed in geo file
Hi,
Actually I had the same problem and in the last few days I put some time into finding the reason why this happens.
The random seeds are actually hard-coded, the reason for the lack of reproducibility comes from a few STL containers that store pointers and were left with the default ordering – which means that the order will be dependent on the pointer addresses – hence the lack of reproducibility.
Here are the modifications that you need to make in order to have full reproducibility:
Note that these are made with respect to the source code of Gmsh 2.8.5.
Mesh/meshGFace.cpp --> added ordering to the set
1080c1080
< std::set<MVertex*, MVertexLessThanLexicographic> all_vertices, boundary;
---
> std::set<MVertex*> all_vertices, boundary;
1155c1155
< for(std::set<MVertex*, MVertexLessThanLexicographic>::iterator it = all_vertices.begin();
---
> for(std::set<MVertex*>::iterator it = all_vertices.begin();
1173c1173
< for(std::set<MVertex*, MVertexLessThanLexicographic>::iterator it = all_vertices.begin();
---
> for(std::set<MVertex*>::iterator it = all_vertices.begin();
----------------
Mesh/meshGFaceBDS.cpp --> defined what happens when we have two identical values in the sort
482,489d481
< bool edges_sort (std::pair<double, BDS_Edge*> a , std::pair<double, BDS_Edge*> b)
< {
< if (a.first == b.first)
< return ((*a.second) < (*b.second));
< else
< return (a.first < b.first);
< }
<
505c497
< std::sort(edges.begin(), edges.end(), edges_sort);
---
> std::sort(edges.begin(), edges.end());
558c550
< std::sort(edges.begin(), edges.end(), edges_sort);
---
> std::sort(edges.begin(), edges.end());
----------------
Mesh/meshGRegion.cpp --> added ordering to the set
1417c1417
< static void getAllBoundingVertices(GRegion *gr, std::set<MVertex*, MVertexLessThanLexicographic> &allBoundingVertices)
---
> static void getAllBoundingVertices(GRegion *gr, std::set<MVertex*> &allBoundingVertices)
1440c1440
< std::set<MVertex*, MVertexLessThanLexicographic> allBoundingVertices;
---
> std::set<MVertex*> allBoundingVertices;
1443c1443
< std::set<MVertex*, MVertexLessThanLexicographic>::iterator itv = allBoundingVertices.begin();
---
> std::set<MVertex*>::iterator itv = allBoundingVertices.begin();
1673,1680d1672
< struct GFaceOrderedByTag
< {
< bool operator() (const GFace* first, const GFace* second) const
< {
< return (first->tag() < second->tag());
< }
< };
<
1713c1705
< std::set<GFace*, GFaceOrderedByTag> mySet;
---
> std::set<GFace*> mySet;
----------------
That’s about it.
It would be nice if these modifications could be added to the SVN version.
Cheers,
Serban
From: gmsh [mailto:gmsh-bounces at ace20.montefiore.ulg.ac.be] On Behalf Of David Bernstein
Sent: 02 November 2014 00:45
To: gmsh at geuz.org<mailto:gmsh at geuz.org> Geuzaine
Subject: [Gmsh] Setting random seed in geo file
Sorry, I missed this post back in May. What is the geo file command to set the global random number seed?
Thanks,
Dave
Hello,
This issue has been fixed in the last versions. What is the version you are using ?
JFR
Le 22 mai 2014 à 23:29, David Bernstein <david at terafrac.org<http://www.geuz.org/mailman/listinfo/gmsh>> a écrit :
> Hi Everyone, I’m using Gmsh as a backend mesh generator in a project and it’s been working very well so far. One issue that we’ve encountered is reproducing a problem from a given set of simulation input parameters because Gmsh produces a different mesh every time it’s run with the same input.
>
> I’ve looked through the documentation and have not been able to find a way to set a random number seed so that the same mesh is produced every time for a given input .geo file. If anyone knows a way to do this please let me know.
>
> Thanks,
> Dave
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it has not been intercepted or amended nor that it is virus-free.
This e-mail is covered by the Electronic Communication Privacy Act, 18 U.S.C. Section 2510-2521 and may be legally privileged. If you have received this transmission in error, please notify the original sender immediately by return e-mail or by telephone at the telephone number provided above and delete/trash the original message from your system. Thank you for your assistance. The information contained herein is confidential information provided only for the use of the individual or entity for whom it was intended. If the reader of this message received it in error, is not the intended recipient, or if an attachment is made in error, the reader is hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited.
This e-mail is covered by the Electronic Communication Privacy Act, 18 U.S.C. Section 2510-2521 and may be legally privileged. If you have received this transmission in error, please notify the original sender immediately by return e-mail or by telephone at the telephone number provided above and delete/trash the original message from your system. Thank you for your assistance. The information contained herein is confidential information provided only for the use of the individual or entity for whom it was intended. If the reader of this message received it in error, is not the intended recipient, or if an attachment is made in error, the reader is hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited.
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