Main driver and input parsing

TL;DR

In this tutorial, we run the following commands:

cd examples/poisson
../../bin/main -i poisson.yml
../../bin/main -i poisson.yml -f visualization/file_path/prefix=other_output

bin/main is the main executable that handles the entire workflow from sample generation to ROM prediction.

Syntax:

main -i input_file -f key1=val1:key2=val2:...

YAML input file

bin/main mainly takes the options from a YAML-based input file. One example of running a full order model (FOM) single prediction of Poisson equation can be found in examples/poisson. From the built directory,

cd examples/poisson
../../bin/main -i poisson.yml

In essence, this reads a mesh file meshes/test.2x2.mesh, refines it 5 times, and solves FOM Poisson equation with a parameterized problem poisson0. The corresponding solution is visualized with paraview file named paraview_output, shown as below:

Overwriting an input option with forced input

It is possible to overwrite an input option in runtime, not changing the original input file. This can be done by using forced input argument. The syntax is:

main -i input_file -f key1=val1:key2=val2:...

The command above will read the option from input file, overwrite the option key1, key2, ... to have a value val1, val2, ... respectively, then run the normal workflow. The YAML levels of key1 is specified by /. For example, the file name for visualization is set in the examples/poisson/poisson.yml as

visualization:
  file_path:
    prefix: paraview_output

If we want to change the file name of the visualization on runtime, we can run the following command:

../../bin/main -i poisson.yml -f visualization/file_path/prefix=other_output

This will save the visualization at other_output, instead of the original paraview_output. This does not change the input file itself.