Faq

Of course, every single package have its own specificities and advantages. I think, the logic is slightly different in the sense that the main goal of GETFEM++ is to be able to handle virtually any FEM, in any number of dimensions.

• The Deal.II library is restricted by design to lines/quadrangles/hexahedrons. It provides tool for mesh generation, parallelization and mesh refinements, has adaptivity as the fundamental principle of the library, and is working on hp-methods (1 <= p <= 4).

• Getfem++ provide a large set of pre-programmed methods. It is possible to use Getfem++ without knowing the details of implementation of finite element methods since they are described with a character string like "PK(N,K)" and the MATLAB interface hides all the c++ internals for people who don't want to deal with C++.

  Getfem++ is more flexible, since it provides separate basic descriptions of Finite Element methods, geometric description and integration methods. This means that you can either choose any pre-programmed fem with any geometric transformation (linear, quadratic ...) and any integration method defined on the same geometric element or define your own methods. If you define properly a new finite element method on the reference element you will be able to use it with any geometric transformation.

  Getfem++ can handle FEMs of any dimension, and this dimension is not fixed at compile-time (it is not a template parameter).

  On the other side Getfem++ is not parallelized and does not have mesh generations tools.

You should disable OpenGL rendering. It won't slow the drawing, but these artifacts ( inconsistant orientation of faces) will disappear.

set(gcf,'Renderer','zbuffer');

If you want to completely disable OpenGL rendering in Matlab, you can put opengl neverselect in your ~/matlab/startup.m.

Unfortunatly, linking a big c++ library with matlab via mex-files has proven to be quite unstable. There are many issues with dynamic libraries, exceptions, dynamic casting etc.

Starting with getfem 1.5, two options are available for getfem-matlab:

• A giant-mex C++ file (default), containing everything. It works in most of the cases, but not all (for example icc won't build a correct mex-file with matlab 6.5)
• A very small C mex-file, which communicates with an external process (the getfem_sever executable). Communications between matlab and the getfem_server use RPC (Remote Procedure Calls). The advantage is that getfem and matlab process are completly separated (they could even run on different machines). Hence it is much easier to pin-point problems in getfem or matlab, and to debug them.

The fix for that problem, using LD_PRELOAD, is explained here.