# What’s New in *GetFEM* 4.3¶

This release is a transitional one until next version 5.0. The new high-level generic assembly based on a weak form language is working and usable. However, the basic model bricks still use the old generic assembly and the new assembly is for the moment incompatible with a few things (Nitsche bricks and time dispatcher bricks).

Released version, 2014/07/14.

The main changes are:

- The introduction of the new high-level generic assembly, the corresponding model bricks and the associated symbolic differentiation which allows to describe non-linear coupled problems in a very easy way.
- The introduction of interpolate transformations in the weak form language to deal with the assembly of terms on different meshes or part of meshes. Example of applications : mortar methods, periodic boundary conditions, large sliding contact conditions
- A large sliding contact with friction brick is now working (work of Konstantinos Poulios and Yves Renard) and will be extended soon.
- A support for Nitsche type method for Dirichlet and contact conditions. The corresponding model bricks will certainly evolve to incorporate the use of the high-level generic assembly.
- A torus_mesh_fem object allowing to easily transform 3D problems into axi-symmetric ones (work of Lim Liang Jin).
- New im_data objects to store and interpolate data on Gauss points of an integration method (work of Lim Liang Jin).
- Multithreaded assembly (Work of Andriy Andreykiv)
- New hyperelastic laws implemented and necessary tools in the high-level generic assembly to describe new potentials (matrix invariants …)
- Allowing tensor field for mesh_fem objects
- Many bug fixes.