# I use DMplex for reading GMSH meshes, how to save in Freefem format? **URL:** \ **Category:** General Discussion\ **Created:** [June 30, 2022, 4:32pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861 "2022-06-30T16:32:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![felric](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@felric](https://community.freefem.org/u/felric)\ **Post date:** [June 30, 2022, 4:32pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/1 "2022-06-30T16:32:05Z")
Dear sir, I need to import a GMSH mesh comprising some physical volumes/surfaces. Following your suggestion, I tried to use DMplex instead of standard freefem mesh loader, as often suggested by you. Now, after some effort I was able to generate a mesh (version 4.1) and apparently no errors reading it with DMplex. However, I am unable to save the mesh in Freefem format: if I add the line: savemesh(Th,“meshSrc.mesh”); then segmentation fault appears. Please notice that since PETSc seems to require MPI, and since I am working on Windows, I used: “mpiexec.exe -np 2 FreeFem+±mpi.exe meshtest5.edp” Thanks very much in advance Riccardo [meshtest5.edp](https://community.freefem.org/uploads/short-url/baSJVDvSXmQhMT4QdEi0seQsVWW.edp) (668 Bytes) [tritrasd.zip](https://community.freefem.org/uploads/short-url/6PWJ60IUHSRrhL91Bcgr95H3mIP.zip) (215.7 KB) ---
**Author:** ![aszaboa](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/aszaboa/32/2918_2.png) [@aszaboa](https://community.freefem.org/u/aszaboa)\ **Post date:** [June 30, 2022, 8:28pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/2 "2022-06-30T20:28:21Z")
Hi, I tested you code and I get no segmentation fault. I am using FreeFem v4.11. If you are using an older FreeFem version, I suggest you consider upgrading it. Otherwise, I have no idea what might causes the segmentation fault. ---
**Author:** ![felric](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@felric](https://community.freefem.org/u/felric)\ **Post date:** [June 30, 2022, 10:55pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/3 "2022-06-30T22:55:50Z")
Thanks for your prompt reply! Yes, I am using version 4.11 that I downloaded few days ago. More precisely, I downloaded the PETSc version, already in binary format, for Windows. I tried with: > mpiexec.exe -np 2 FreeFem+±mpi.exe meshtest5.edp > FreeFem+±mpi.exe meshtest5.edp from both PowerShell and Command Prompt. Same answer: > Number of triangle(s) = 14169 > Mesh area = 60978.2 > Border length = 12548.4 > [0]PETSC ERROR: ------------------------------------------------------------------------ > [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, probably memory access out of range […] BUT I ALSO DISCOVERED THAT I HAVE THE SAME PROBLEM ON ANY 3D MESH. HERE A VERY SIMPLE EXAMPLE: This FAILS with seg fault, creating a file “meshCubeDiff.mesh” with size equal to zero: > load “PETSc” // PETSc plugin > macro dimension()3// EOM // 2D or 3D > include “macro\_ddm.idp” // additional DDM functions > int[int] LL = [1,2, 1,2, 1,1]; > mesh3 Tht = cube(10,10,10, [x, y, z], label = LL); // global mesh > savemesh(Tht,“meshCubeDiff.mesh”); However THIS WORKS LIKE A CHARM (PERFECTLY), creating two mesh files: > load “PETSc” // PETSc plugin > macro dimension()2// EOM // 2D or 3D > include “macro\_ddm.idp” // additional DDM functions > mesh Th2D = square(50, 10, [5 \* x, y]); > savemesh(Th2D,“meshSquareDiff.mesh”); THE ONLY DIFFERENCE I SEE IS THAT THE FIRST IS A 3D MESH WHILE THE SECOND IS A 2D MESH. [Square.edp](https://community.freefem.org/uploads/short-url/zJLyOgaaj5sRn2YgRofG1lNYMYj.edp) (313 Bytes) [Cube.edp](https://community.freefem.org/uploads/short-url/1HsKWxU5ccWeuO8i5HaXgj4blgc.edp) (364 Bytes) These are very simple examples. Do you see the same results? Thanks again Best regards Riccardo ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [July 1, 2022, 6:16am UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/4 "2022-07-01T06:16:08Z")
This is a Windows-specific issue, I believe. Do you have access to another machine? ---
**Author:** ![felric](https://avatars.discourse-cdn.com/v4/letter/f/5f8ce5/32.png) [@felric](https://community.freefem.org/u/felric)\ **Post date:** [July 1, 2022, 5:28pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/5 "2022-07-01T17:28:35Z")
Dear sir, I tried to reinstall freefem++ (“ **FreeFem+±4.11-win64-petsctest.exe** ”) but no change. I have Ubuntu on a **Windows Subsystem for Linux** (WSL 2.0). I tried to build it. Everythings was fine, until it failed to set an environment variable because it pointed to the Windows system (I guess, because it is a subsystem). Finally the “make check” failed. ---
**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\ **Post date:** [July 1, 2022, 5:45pm UTC](https://community.freefem.org/t/i-use-dmplex-for-reading-gmsh-meshes-how-to-save-in-freefem-format/1861/6 "2022-07-01T17:45:55Z")
If you try on a non-Windows machine, you’ll see it works. I don’t know why it’s failing there, I don’t have a fix available, sorry.