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

[Guangran Kevin Zhu]

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?

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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