Philosophy of examples and how to run them

The idea of our examples is to present the functionality of the library in an accessible and incremental manner. The examples present different solutions to problems ranging in difficulty from the simple Poisson's equation to more specific examples, such as Fluid mechanics. Each examples consists of a name, e.g. poisson_implicit_dirichlet_2D and its corresponding

• source code, e.g. poisson_implicit_dirichlet_2D.cpp
• plot script, e.g. poisson_implicit_dirichlet_2D.m

Additional appropriately named input files might be present for more complicated examples and similarly named output files might be produced. The examples and their plot scripts are intended to work out of the box, so the reader can simply run the examples on their machine. The procedure for running examples is simple and the same for all examples. The accompanying plot scripts can be run with Matlab or octave and they produce the figures the reader sees in the Examples category of this wiki.

Let us now illustrate the process of running an example poisson_implicit_dirichlet_2D.

First the example needs to be built (compiled). The building is done in the same build/ directory where medusa was build. To build and run the example, simply execute

make poisson_implicit_dirichlet_2D_run  # builds and runs your example

to compile and run your example. On first compilation, the whole library might compile as well, if not compiled previously, so it might take longer than usual. Compiled binary used to run the example is placed next to the example source file. If only make poisson_implicit_dirichlet_2D (without _run) the example is built, but not run.

To build all examples, you can just run

make examples  # or "make examples_run" to also run them

To run the built example again, go back to the initial folder where the source code for your example was, and run

./poisson_implicit_dirichlet_2

The output will be saved in the same folder as the binary and the source file.

After, just run the corresponding plot script example_name.m and you should see a figure, usually showing the solution.

Standalone compilation The examples can then be compiled manually using e.g. `g++`, provided that appropriate include and library paths are set and the `medusa_standalone` library is specified for linking.

Example command to be run from `poisson_equation` directory:

g++ -o poisson_dirichlet_1D poisson_dirichlet_1D.cpp -I ../../include -Wall -O3 -L ../../bin -lmedusa_standalone

The compiled example can be run simply as

./poisson_dirichlet_1D

Some more feature specific examples are found in the technical documentation and in the unit tests.