Wrong "element_size" in GWFL for line element in 2D

Development
1

@yves.renard just discovered this inconsistency we need to fix:

Python 3.13.2 (main, Feb  5 2025, 01:23:35) [GCC 14.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import getfem as gf
>>> m=gf.Mesh("cartesian",[0,2,4])
>>> m.transform([1,0])
>>> mim = gf.MeshIm(m, 3)
>>> gf.asm_generic(mim, 0, "Print(element_K(1))", -1)
Print term element_K(1) on Gauss point 0/2 of element 0: sizes () vector(1) [ 2 ]
Print term element_K(1) on Gauss point 1/2 of element 0: sizes () vector(1) [ 2 ]
Print term element_K(1) on Gauss point 0/2 of element 1: sizes () vector(1) [ 2 ]
Print term element_K(1) on Gauss point 1/2 of element 1: sizes () vector(1) [ 2 ]
8.0
>>> gf.asm_generic(mim, 0, "Print(element_K(2))", -1)
Print term element_K(2) on Gauss point 0/2 of element 0: sizes () vector(1) [ 0 ]
Print term element_K(2) on Gauss point 1/2 of element 0: sizes () vector(1) [ 0 ]
Print term element_K(2) on Gauss point 0/2 of element 1: sizes () vector(1) [ 0 ]
Print term element_K(2) on Gauss point 1/2 of element 1: sizes () vector(1) [ 0 ]
0.0
>>> gf.asm_generic(mim, 0, "Print(element_size)", -1)
Print term element_size on Gauss point 0/2 of element 0: sizes () vector(1) [ 0 ]
Print term element_size on Gauss point 1/2 of element 0: sizes () vector(1) [ 0 ]
Print term element_size on Gauss point 0/2 of element 1: sizes () vector(1) [ 0 ]
Print term element_size on Gauss point 1/2 of element 1: sizes () vector(1) [ 0 ]
2

Dear Kostas,

There were indeed an error in the function convex_radius_estimate of getfem_mesh.cc : intervertion of min and max eigen value. Strange that it has not been detected before ! I commited a fix.

Yves