[Gmsh] gmsh 2.0.8 aborts or segfaults

[Werner Scholz]

Hi Christophe!

This is a follow-up on the previous discussion (see below) but I have a
new problem.

It seems that I was able to fix problem (1) and now the points are
sufficiently far apart to keep the mesh algorithms happy. (I think I
achieved this just by scaling the whole model.)

However, now in some cases gmsh does not want to save the mesh even
though the meshing itself was successful! Instead gmsh throws the error
message

"Unable to open file 'media651b.msh'".

I think I made sure there are no problems with disk space, read
protected files of the same name, or other trivial reasons for this problem.

Please find attached two examples (geo files gz compressed):

media650.geo		gmsh geo file which works fine with "gmsh -3"
media650.geo.png	snapshot of the model

media651b.geo		gmsh geo file which triggers the problem
media651b.geo.png	snapshot of the model

media800.geo		larger gmsh geo file which triggers the problem

There is only a tiny difference between the media650 and media651 models 
in the upper left corner: model651b has one "cell" more than model650.

Meshing with "gmsh -3" and NETGEN works fine in both cases.

Just with media651b.geo gmsh does not save the mesh properly (both from
the command line and in the GUI). To my surprise, my self-compiled 
version of gmsh saves the mesh of media651b correctly (it uses netgen 
too, but the 3D meshing performs a different number of swaps). However, 
both the gmsh Linux binary from the gmsh website as well as my 
self-compiled version fail with media800.geo with the above mentioned 
error message.

Any help would be greatly appreciated.

Thanks,

Werner


Christophe Geuzaine wrote:
> 
> Hi Werner - After a quick investigation it seems that the problem is
> twofold:
> 
> (1) some points in your file are very close to each other (almost
> identical): this leads to the creation of extremely "thin" surfaces in
> the extrusion, which in turns makes the 2D and 3D mesh algorithms unhappy
> 
> (2) your file also seems to trigger a weird bug in our code (the "Weird
> point" message)
> 
> Could you regenerate a .geo file that fixes (1)? Then we could
> investigate (2) in more detail.
> 
> Christophe
> 
> magpar wrote:
>> Hello again,
>>
>> Just a quick follow-up on the problem reported previously:
>>
>> The second geo file attached to the previous email, which shows the 
>> problems, has a bunch of distorted volumes, which show up when 
>> rendering the geo file in gmsh. Usually my scripts remove these 
>> volumes and they do not appear to cause the segfault problems.
>>
>> Attached another example, which causes gmsh to segfault. This time 
>> without the distorted volumes.
>>
>> When opening this geo file with gmsh in the graphical user interface, 
>> gmsh throws these errors:
>>
>> gmsh media_p03.geo
>>
>> Info    : Reading 'media_p03.geo'
>> Error   : Weird point 554 in Coherence
>> Error   : Weird point 554 in Coherence
>> Error   : Weird point 510 in Coherence
>> Error   : Weird point 510 in Coherence
>> Error   : Weird point 510 in Coherence
>> [...]
>>
>> However, gmsh does display a reasonable geometry.
>>
>> Meshing leads to the segfault:
>>
>> gmsh -3 media_p03.geo
>> (Mesh.Algorithm3D=4;)
>>
>> Info    : 16 points, 23 elements
>> Info    : Meshing volume 23 (Netgen)
>> Fatal   : Segmentation violation (invalid memory reference)
>>
>> gmsh -3 media_p03.geo
>> (Mesh.Algorithm3D=1;)
>>
>> Info    : Meshing volume 473 (Delaunay)
>> Info    : Meshing volume 474 (Delaunay)
>> Fatal   : Segmentation violation (invalid memory reference)
>>
>>
>> Thanks in advance for any help.
>>
>>
>> Werner
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> gmsh mailing list
>> gmsh at geuz.org
>> http://www.geuz.org/mailman/listinfo/gmsh
> 
> 


-- 
magpar - Parallel Finite Element Micromagnetics Package
WWW:    http://magnet.atp.tuwien.ac.at/scholz/magpar/
email:  magpar at magnet.atp.tuwien.ac.at
list:   majordomo at magnet.atp.tuwien.ac.at


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