public Dictionary <Node, IList <IDofType> > GetModelRigidBodyNodeConstraints(Model model)
 {
     return(FEMMeshBuilder.GetConstraintsOfDegenerateRVEForNonSingularStiffnessMatrix_withRenumbering(model, mp.hexa1, mp.hexa2, mp.hexa3, renumbering_vector_path));
     //TODO:  Pithanws na epistrefetai apo GetModelAndBoundaryNodes ... AndConstraints.
 }