For linear stationary problems it can be of interest to see the solution for several different loads F (right-hand side of the basic PDE) on the same structure (a model where the geometry and materials are defined and do not change). Typically this is used for studies using linear combinations of different loads — load cases. It is then possible to solve for these load cases in a computationally efficient way because there is no need to reassemble the stiffness matrix. Varying constraints can also be part of a general load case definition, and the COMSOL Multiphysics software supports load cases that are combination of loads, with optional weights, and constraints.