.. _clawpack-quickstart:

Clawpack Quickstart guide
=========================

See also:

 * `Clawpack Documentation <http://www.clawpack.org/users/>`_

If you use using the class VM, the Clawpack software is in the directory
`clawpack-4.x`.   If you are using it on your own computer, see the 
`Installation instructions
<http://depts.washington.edu/clawpack/users-4.6/installing.html>`_.

Open a terminal and do (the first `$` indicates the Linux prompt)::

    $ cd $CLAW

This should take you into the directory `clawpack-4.x`.  (The *environment
variable* `$CLAW` should already be set properly on the VM.)

To try out an advection example::

    $ cd apps/advection/1d/example1
    $ make .plots

With luck this will automatically do the following:

* Compile the Fortran code

* Create some files ending with extension `.data` that are needed by the
  Fortran code.  (Based on parameter values set in the Python script
  `setrun.py`)

* Run the Fortran code and produce a directory named `_output` that has the
  solution at various times from the computation.

* Run a plotting program to produce a directory named `_plots` that contains
  images `*.png` of the solution at various times and files `*.html` that 
  allow you to easily view these images.  Exactly what is plotted is
  determined by the file `setplot.py`.

If you now give the command::

    $ firefox _plots/_PlotIndex.html

you should be able to view these plots.


Changing parameters
-------------------

To try changing a parameter, edit the file `setrun.py` and then type::

    $ make .plots

and reload the plot file in firefox.  

Some things you might try changing:

* `clawdata.order`  Change the value to 1 for the first order upwind method.

* `clawdata.mthbc_xlower` and `clawdata.mthbc_xupper`.  Change both values
  to 2 to impose periodic boundary conditions.

* `clawdata.tfinal` determines the final time you solve to.

Next steps
----------

The directory `$CLAW/apps` contains a number of other applications you might
want to experiment with.  You might next look at the acoustics examples in
`$CLAW/apps/acoustics/1d/example1`.

Note that the Riemann solver used for each case is in a Fortran file in the
corresponding directory with the name `rp1.f`.  

See the `Clawpack Documentation <http://www.clawpack.org/users/>`_
for more information about changing parameters and plotting the results.