CLAW_PIX
CLAWPACK Q Files
Solution Display
PNG Images

CLAW_PIX is a MATLAB program which plots CLAWPACK "Q" files.

That is, it reads a set of files, each containing the values of a scalar function of X, whose behavior is controlled by a hyperbolic PDE. For each data set, the program displays a plot of the solution, and creates a PNG file of that plot. The set of PNG files can be used to create an animation, by Quicktime Pro, for instance.

The "Q" files have 'consecutive' names, such as "fort.q0000", "fort.q0001" and so on. The user only has to tell the program the name of the first file; it will automatically continue to process files until it reaches the end of the sequence of names.

Note that there is already a MATLAB program, called CLAWPACK_PLOT, which can display results for 1d, 2d or 3d problems, and is not limited to scalar data in the 1d case. So why did I write this program? Primarily because I found CLAWPACK_PLOT awkward to use and was unhappy that it did not use a uniform scale for all the images, making animations worthless.

Usage:

claw_pix q_file

q_file is the first file in a numerically related sequence.

Related Data and Programs:

CLAWPACK is a library of FORTRAN77 routines for the solution of wave propagation to hyperbolic partial differential equations in 1, 2 or 3 spatial dimensions.

CLAWPACK_PLOT is a library of MATLAB routines for the visualization of results obtained from CLAWPACK.

PNG files are a common and useful format for storing single images, out of which animations can be constructed.

Source Code:

• claw_pix.m, the main program for creating the images and PNG files;
• file_exist.m, is TRUE if a file exists;
• file_name_ext_swap.m, replaces the extension of a file;
• file_name_inc.m, "increments" the name of a file;

Examples and Tests:

In solving a problem, CLAWPACK generates a sequence of data files containing the solution at successive time steps. These files are what CLAW_PIX needs as input.

• fort.q0000, Q file 0.
• fort.q0001, Q file 1.
• fort.q0002, Q file 2.
• fort.q0003, Q file 3.
• fort.q0004, Q file 4.
• fort.q0005, Q file 5.
• fort.q0006, Q file 6.
• fort.q0007, Q file 7.
• fort.q0008, Q file 8.
• fort.q0009, Q file 9.
• fort.q0010, Q file 10.

The PNG images were created automatically by the program:

• fort.q0000.png, time step 0 image;
• fort.q0001.png, time step 1 image;
• fort.q0002.png, time step 2 image;
• fort.q0003.png, time step 3 image;
• fort.q0004.png, time step 4 image;
• fort.q0005.png, time step 5 image;
• fort.q0006.png, time step 6 image;
• fort.q0007.png, time step 7 image;
• fort.q0008.png, time step 8 image;
• fort.q0009.png, time step 9 image;
• fort.q0010.png, time step 10 image;

You can go up one level to the MATLAB source codes.