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## CLAWPACK Sample Code

Burgers' equation with a transonic rarefaction wave. Local Lax-Friedrichs method is implemented in [code:rp1llf.f], or standard Lax-Friedrichs by commenting out one line in that file. Example [book/chap12/llf] to accompany the book
[www.clawpack.org/book.html Finite Volume Methods for Hyperbolic Problems] by R. J. LeVeque. Converted to [www.clawpack.org Clawpack 4.4] form in 2009.

#### Plots of results

After running this code and creating plots via "make .plots", you should be able to view the plots in [link: _plots/_PlotIndex.html].

#### Fortran files

[code: Makefile]
Determines which version of fortran files are used when compiling the code with make and specifies where output and plots should be directed. Type "make .help" at the Unix prompt for options.
[code: driver.f]
The driver routine allocates storage and then calls the main Clawpack routine.
[code: setprob.f]
A routine by this name is called by the library routine [clawcode: clawpack/1d/lib/claw1ez.f] and is generally used to set any values needed for the specific problem being solved.
[code: rp1llf.f]
This is the Riemann solver, which takes the \$q\$ values stored in the arrays ql and qr and returns the waves in the array wave and speeds in the array s that result in solving the Riemann problem at each cell interface, and the fluctuations amdq and apdq. See [claw:doc/rp1.html] for more information about 1d Riemann solvers.
[code: qinit.f]
This subroutine sets the initial data at time \$t=0\$.

#### Python files

[code: setrun.py]
This file contains a function that specifies what run-time parameters will be used.
[code: setplot.py]
This file contains a function that specifies what plots will be done and sets various plotting parameters.

#### Data files

Warning: These files are generally changed when setting up a run and the versions here may not be the ones actually used.
[code: claw.data]
This file contains a number of parameter values that are used by CLAWPACK. The values in this file are read by the library routine [clawcode: clawpack/1d/lib/claw1ez.f]. Each line contains one or more values to be read in, followed by comments that are ignored by the Fortran code but may be used by Pythons scripts. Some parameters that you might want to modify are described in the [http://kingkong.amath.washington.edu/clawpack/users documentation].
[code: setprob.data]
This file may contain various parameters used in setting the initial conditions or otherwise setting up the problem.

#### Library routines

In addition to the Fortran routines in this library, several library routines from [claw:clawpack/1d/lib] are used. See the [code: Makefile] to determine which ones are used. end_html