[Gmsh] Failed to mesh in 2D polygon with 2nd order elements

[Christophe Geuzaine]

Guangran Kevin Zhu wrote:
> Hello,
>  
> I am using GMSH 2.0.8 on Windows XP. GMSH failed to generate 2nd order 
> elements with a simple 2D polygon, while using GMSH 1.6 was successful. 
> Has anyone ecountered a similar problem on other platforms? What is the 
> work around?

Works over here...

>  
> I list the geo file and the error message below.
>  
> Kevin
>  
> ===================================================
> // Gmsh project created on Tue Oct 30 14:59:54 2007
> Point(1) = {0.065,0.126,0,0.1};
> Point(2) = {0.093,0.35,0,0.1};
> Point(3) = {-0.029,0.063,0,0.1};
> Point(4) = {-0.061,0.061,0,0.1};
> Point(5) = {-0.07,0.043 ,0,0.1};
> Point(6) = {-0.05,0.018,0,0.1};
> Point(7) = {-0.047,0.044,0,0.1};
> Line(1) = {3,4};
> Line(2) = {4,5};
> Line(3) = {5,6};
> Line(4) = {6,7};
> Line(5) = {7,3};
> Line Loop(6) = {2,3,4,5,1};
> Plane Surface(7) = {6};
> ====================================================
>  
> Error message
> ====================================================
> Warning : Triangle 578 (15 1 5) has negative Jacobian
> Warning : Triangle 582 (0 170 10) has negative Jacobian
> Warning : Triangle 585 (176 22 19) has negative Jacobian
> Warning : Triangle 595 (180 13 6) has negative Jacobian
> Warning : Triangle 618 (8 13 188) has negative Jacobian
> Warning : Triangle 625 (190 23 11) has negative Jacobian
> Error   : Some triangles have negative Jacobians in surface 7
> ====================================================
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine