Running an example

Many examples of Clawpack simulations can be seen in the Galleries of all Clawpack applications.

Using PyClaw. To run an example and plot the results using PyClaw, simply do the following (starting from your clawpack directory):

cd pyclaw/examples/euler_2d
python shock_bubble_interaction.py iplot=1

That’s it. For next steps with PyClaw, see PyClaw Basics.

Using Classic. First ensure that you have Set environment variables. A simple 1-dimensional acoustics equations can be solved using the code in $CLAW/classic/examples/acoustics_1d_example1, as illustrated in gallery_classic_amrclaw.

Move to this directory via:

cd $CLAW/classic/examples/acoustics_1d_example1

You can try the following test in this directory, or you may want to first make a copy of it (see the instructions in Copying an existing example).

The Makefiles are set up to do dependency checking so that in many application directories you can simply type:

$ make .plots

and the Fortran code will be compiled, data files created, the code run, and the results plotted automatically, resulting in a set of webpages showing the results.

However, if this is your first attempt to run a code, it is useful to go through these steps one at a time, both to understand the steps and so that any problems with your installation can be properly identified.

You might want to start by examining the Makefile. This sets a number of variables, which at some point you might need to modify for other examples, see Clawpack Makefiles for more about this. At the bottom of the Makefile is an include statement that points to a common Makefile that is used by most applications, and where all the details of the make process can be found.

To compile the code, type:

$ make .exe

If this gives an error, see Trouble running “make .exe”.

This should compile the example code (after first compiling the required library routines) and produce an executable named xclaw in this directory.

Before running the code, it is necessary to also create a set of data files that are read in by the Fortran code. This can be done via:

$ make .data

If this gives an error, see Trouble running “make .data”.

This uses the Python code in setrun.py to create data files that have the form *.data.

Once the executable and the data files all exist, we can run the code. The recommended way to do this is to type:

$ make .output

If this gives an error, see Trouble running “make .output”.

Before running the code a subdirectory _output is created and the output of the code (often a large number of files) is directed to this subdirectory. This is convenient if you want to do several runs with different parameter values and keep the results organized. After the code has run you can rename the subdirectory, or you can modify the variable OUTDIR in the Makefile to direct results to a different directory. See Clawpack Makefiles for more details. Copies of all the data files are also placed in the output directory for future reference.

Plotting the results. Once the code has run and the files listed above have been created, there are several options for plotting the results.

To try the Python tools, type:

$ make .plots

If this gives an error, see Trouble running “make .plots”.

If this works, it will create a subdirectory named _plots that contains a number of image files (the *.png files) and a set of html files that can be used to view the results from a web browser. See plotting_makeplots for more details.

An alternative is to view the plots from an interactive Python session, as described in the section Interactive plotting with Iplotclaw.

If you wish to use Matlab instead, see Plotting using Matlab.

Other visualization packages could also be used to display the results, but you will need to figure out how to read in the data. See fortfiles for information about the format of the files produced by Clawpack.