Example b33 - coupled bidomain electromechanics. This example solves the bidomain equations on a 2d domain which is coupled to a mechanical deformation from the release of intracellular calcium. The VanCapelle Durer ionic current model is used. The mesh is 4*4 elements with 9*9 grid points per element. An analytic solution is used to get the extracellular boundary conditions. Solution is by sparse LU factorisation.