README.html Source file:   README.txt Directory:   /Users/rjl/git/rjleveque/clawpack-4.6.3/book/chap12/efix Converted:   Mon Jan 21 2013 at 20:15:32   using clawcode2html This documentation file will not reflect any later changes in the source file.

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## CLAWPACK Sample Code

Burgers' equation with a transonic rarefaction wave.

Comparison of results obtained with or without the entropy fix. This is set in the Riemann solver rp1.f [.html] by modifying the variable efix and recompiling.

Note: also try changing mx in setrun.py [.html] to an odd value (e.g. 61 instead of 60). Then there is one grid cell with the value 0.5 at x=0 and a different weak solution is obtained.

Note: The solution also looks much smoother if you set order=2 in rp1.f [.html] instead of order=1.

Example [book/chap12/efix] to accompany the book
Finite Volume Methods for Hyperbolic Problems by R. J. LeVeque.

Converted to 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 _plots/_PlotIndex.html .

#### Fortran files

Makefile [.html]
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.

driver.f [.html]
The driver routine allocates storage and then calls the main Clawpack routine.

setprob.f [.html]
A routine by this name is called by the library routine clawpack/1d/lib/claw1ez.f [.html] and is generally used to set any values needed for the specific problem being solved.

rp1.f [.html]
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 $CLAW/doc/rp1.html for more information about 1d Riemann solvers. qinit.f [.html] This subroutine sets the initial data at time$t=0$. #### Python files setrun.py [.html] This file contains a function that specifies what run-time parameters will be used. setplot.py [.html] This file contains a function that specifies what plots will be done and sets various plotting parameters. #### Data files Warning: These files are generally changed when setting up a run and the versions here may not be the ones actually used. claw.data [.html] This file contains a number of parameter values that are used by CLAWPACK. The values in this file are read by the library routine clawpack/1d/lib/claw1ez.f [.html]. Each line contains one or more values to be read in, followed by comments that are ignored by the Fortran code but may be used by Pythons scripts. Some parameters that you might want to modify are described in the documentation . setprob.data [.html] This file may contain various parameters used in setting the initial conditions or otherwise setting up the problem. #### Library routines In addition to the Fortran routines in this library, several library routines from$CLAW/clawpack/1d/lib are used. See the Makefile [.html] to determine which ones are used.