[Gmsh] freefem

Geordie McBain gdmcbain at freeshell.org
Fri Jun 11 01:25:21 CEST 2010

2010/6/11 Luis Casillas <casillasluis at lanl.gov>:
> Hello,
> I'm trying to export a mesh from gmsh to freefem++, I tried to use the
> gmshload command in freefem but no luck, now I'm trying using the medit
> format but also is not working, I would appreciate any tip,
> thanks
> Luis

Are you working in two or three dimensions?

In two dimensions, I believe FreeFem++ should be able to load a Gmsh
.msh mesh O.K.  The only limitation I've discovered is that the
interpolation operator, e.g. u (x1, y1) to extract the value of the
solution u at the point (x1, y1), doesn't work.

For that reason, you might want to use the MEDIT .mesh format in two
dimensions, but FreeFem++ expects a variation of the MEDIT format
which differs from Frey's (2001) specification; see `Third coordinate
Z not wanted' <http://www.geuz.org/pipermail/gmsh/2010/005247.html>
for the problem and remedy.

In three dimensions, I couldn't get FreeFem++ to load a Gmsh .msh; the
only option is to use the MEDIT .mesh format.  However, this works
easily in three dimensions; no translation is required.

Another issue is that you need to define physical entities for the
domains and boundaries, and then set Mesh.SaveElementTagType=2; see
`Medit file format'

I think this should be enough to get you going; do let me know if I've
forgotten something.