[Gmsh] Problem with 2d background mesh

[Jose Paulo Moitinho de Almeida]

Hello

For the attached geometry and background mesh I am getting strange results 
which start at the 1d mesh and produce different results for 2.0.8 and 2.2.3.

As "usual" I have elements of quite different sizes...

-----------------------------
With 2.2.3 (the version I tested first)

$ gmsh aaa.geo -bgm aaa.bgm -noview a.script

Press 1 -> No nodes are generated on the upper left edge.
Press 2 -> The mesh is "cropped" to the left of the singular point.

$ gmsh bbb.geo -bgm aaa.bgm -noview a.script

(File bbb.geo is the same as aaa.geo, just switched lines 1 and 6).

Press 1 -> Way too many points on the upper left edge.
Press 2 -> The mesh is totally irregular near that edge.

-----------------------------
Switched to 2.0.8

$ gmsh aaa.geo -bgm aaa.bgm -noview a.script

Press 1 -> Same as for aaa.geo with 2.2.3.
Press 2 -> Lots of "Error: Colinear points in circum circle computation", but 
the mesh looks almost good. (1316 nodes, 2630 elements)

$ gmsh bbb.geo -bgm aaa.bgm -noview a.script

Press 1 -> Looks good!
Press 2 -> Again lots of "Error: Colinear points in circum circle 
computation", the mesh looks good (1314 nodes, 2626 elements)

-----------------------------

Changing the algorithm does not seem to help. But the problem is really on 
providing info about the background mesh to the 1d generator, correct?

I tried to look at the source code (BGM_MeshSize?), but must admit my failure 
on understanding "what is coming from where".

Any suggestions?

Thanks

ZP
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Point(1) = {0,0,0,1};
Point(2) = {1,0,0,1};
Point(3) = {1,0.5,0,1};
Point(4) = {1,0.8,0,1};
Point(5) = {1,1,0,1};
Point(6) = {0.5,1,0,.001};
Point(7) = {0,1,0,.001};
Point(8) = {0,0.8,0,1};
Point(9) = {0.5,0.8,0,1};
Point(10) = {0.5,0.5,0,1};
Point(11) = {0,0.5,0,1};
Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,5};
Line(5) = {5,6};
Line(6) = {6,7};
Line(7) = {7,8};
Line(8) = {8,9};
Line(9) = {9,10};
Line(10) = {10,11};
Line(11) = {11,1};
Line Loop(12) = {1,2,3,4,5,6,7,8,9,10,11};
Plane Surface(13) = {12};
Physical Surface(14) = {13};
Physical Line(101) = {1};
Physical Line(102) = {2};
Physical Line(103) = {3};
Physical Line(104) = {4};
Physical Line(105) = {5};
Physical Line(106) = {6};
Physical Line(107) = {7};
Physical Line(108) = {8};
Physical Line(109) = {9};
Physical Line(110) = {10};
Physical Line(111) = {11};
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Point(1) = {0,0,0,1};
Point(2) = {1,0,0,1};
Point(3) = {1,0.5,0,1};
Point(4) = {1,0.8,0,1};
Point(5) = {1,1,0,1};
Point(6) = {0.5,1,0,.001};
Point(7) = {0,1,0,.001};
Point(8) = {0,0.8,0,1};
Point(9) = {0.5,0.8,0,1};
Point(10) = {0.5,0.5,0,1};
Point(11) = {0,0.5,0,1};
Line(6) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,5};
Line(5) = {5,6};
Line(1) = {6,7};
Line(7) = {7,8};
Line(8) = {8,9};
Line(9) = {9,10};
Line(10) = {10,11};
Line(11) = {11,1};
Line Loop(12) = {1,2,3,4,5,6,7,8,9,10,11};
Plane Surface(13) = {12};
Physical Surface(14) = {13};
Physical Line(101) = {1};
Physical Line(102) = {2};
Physical Line(103) = {3};
Physical Line(104) = {4};
Physical Line(105) = {5};
Physical Line(106) = {6};
Physical Line(107) = {7};
Physical Line(108) = {8};
Physical Line(109) = {9};
Physical Line(110) = {10};
Physical Line(111) = {11};
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