[Gmsh] Zero volume elements in Delaunay 2d triangulation

[Jose Paulo Moitinho de Almeida]

Hello

I know that the Delaunay triangulation is "experimental", but I was solving 
the problem of face orientation when post-processing the mesh.

Now, when refining the mesh around a singularity I came to an example where I 
get 

$ gmsh ref.geo -algo del2d -2 -bgm ref.bgm
....
Warning : Colinear points in circum circle computation
....

and the resulting mesh has triangles with colinear nodes.

I tried two recent versions (gmsh-2.1.2-cvs-20080312 and 
gmsh-2.1.2-cvs-20080331) which produced slightly different meshes, but the 
same problem by creating (at least) an element (4782 and 4780) with colinear 
(on a vertical line) nodes (173, 174 and 175).

Is it just a problem of parameters? Changing the geometry tolerance had no 
effect.

If it isn't my mistake perhaps this example, with very small elements, can be 
of use in your tests.

Regards

JP Moitinho
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