[Getfem-users] get tangent matrix with matlab interface for non-linear elasticity models?

[Nico Galoppo]

Hi,

I'm trying to look at the tangent matrix after running the tripod demo
(demo_tripod.m) with linear = 0. Like this:

K = gf_mdstate_get(mds, 'tangent_matrix');

Unfortunately, this gives an all-zero sparse matrix:

K =

   All zero sparse: 16764-by-16764

If I do the same thing with linear = 1, it works fine. Is this a known bug?

Also, I've had to disable the source term in this demo to be able to
have the solver converge for non-linear elasticity enabled. If I don't
do it, the solver crashes. I'm assuming it doesn't converge.

I am on Mac OSX (Tiger) with MATLAB version 7.4.0.287 (R2007a) and the
latest getfem++ from the website (3.0.3).


--nico

-- 
Nico Galoppo :: http://www.ngaloppo.org