[Gmsh] possible gmsh bug?

[Peter Vos]

Dear Professors Geuzaine and Remacle,

As part of the Nektar++ (www.nektar.info) project, I wrote a Nektar++- 
to-Gmsh converter in order to visualise the high-order data in 2D.
This did work fine with gmsh version 2.2.0, but it has recently be  
drawn to my attention that the resulting .pos file caused gmsh latest  
release (version 2.3.1) to crash.

An example file that works for version 2.2.0 but not for 2.3.1 can be  
found attached.
The structure of the generated .pos file is typically as follows:
First a "View" which bundles all the quads in the mesh, then a "View"  
of all the triangles and finally the command "Combine  
ElementsFromAllViews" to merge both views.

Looking at the source code, I found out that it is this last call,  
i.e. "Combine ElementsFromAllViews", which causes gmsh 2.3.1 to crash.
More specifically, I think it is the piece of code between line  
666-672 in the file Post/PViewDataList.cpp which prevents the  
interpolation matrices from the second view (i.e. the tri's) to be  
copied to the new combined view. This later on leads to a bus error  
when trying to access 'im[0]' on line 203 of the file Post/ 
PViewDataList.cpp (as the pointer 'im' will not point to anything  
valid for the triangles in the combined view).

I am not sure whether this is a bug in the code or whether it is  
caused by a bad structure of my .pos file. In the latter case, please  
let me know how to better construct my .pos file to avoid this problem.


Looking forward to your talks next week in Norway.

Kind Regards



Peter







Peter Vos
peter.vos at imperial.ac.uk

PhD Research Student
Department of Aeronautics
Imperial College
London



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