In this tutorial, you will learn to use the Expression-assembler of G+Smo, see gsExprAssembler. This powerful tool can be used to assemble a system of equations, given the expressions of a weak formulation.

Relevant source files

The files relevant for using the gsExprAssembler are the following:

gsExprAssembler.h : contains the assembly routines for generic expressions; all performed with the gsExprAssembler,
gsExprEvaluator.h : contains the class that is used to evaluate expressions; gsExprEvaluator,
gsAssemblerOptions.h : contains the gsAssemblerOptions class which is used to define options for the Expression-assembler,
gsExpressions.h : contains classes that are the actual expressions and the arithmetic to evaluate them,
gsExprHelper.h : contains the gsExprHelper class to store evaluation data of expression-related objects,
gsDirichletValues.h : contains classes to evaluate non-homogeneous Dirichlet boundary conditions defined for a space.

From those classes the top three (gsExprAssembler, gsExprEvaluator and gsAssemblerOptions) are the ones that are actually called in your code, wheres the other ones are used under the hood.

Furthermore, for any boundary value problem boundary conditions are to be defined. This happens with the gsBoundaryConditions class.

Example 1: The Poisson Equation

See poisson2_example.cpp

Example 2: The Kirchhoff-Love shell

See kirchhoff-Love_example.cpp