Department of Mathematics and Computing Science
Mathematics research groups
Computational Mechanics and Numerical Mathematics
Numerical Mathematics
            VSM
                   Description and download file
                   Short Manual and example
                   Support

The package VSM (Visualize Sparse Matrix) is a tool to visualize sparse matrices. The tool expects a  matrix in CSR (Compressed Sparse Row) formats either binary or ascii. An m-file to display MATLAB matrices is available in the package. The code is written in C and makes use of the unix X-window environment. The package consisting of the complete source is packed in a tar-file which is to be unpacked by "tar  xvf vsm.tar".  A makefile for building the executable accomponies the code. The code runs already on many different kinds of platforms and is extremely fast. For more details concerning the installation see the README file in package.

Short Manual and examples

After supplying VSM a file it opens a window of the sort displayed below.  At the bottom there are 5 buttons from which the black coloured one is active:

• Quit (obvious)
• Global makes the colouring on basis of the magnitude of the elements in the original matrix
• Local makes the colouring on basis of the magnitude of the elements of a thinned out matrix (set by Min and/or Max)
• Sign lets display the signs of the elements by means of two colours
• Print will produce a black and white plot of the current display into "fig" format. The size of the dots represent the magnitude of the elements. For a colour plot you can make a window dump with xv.

On the right one sees on top the rows and columns displayed. By left clicking and dragging one can zoom in into a desired portion of the matrix.  By right clicking one gets back to the previous plot.  By "Magn" the number of pixels per element are shown. For large matrices more elements  are displayed by one pixel taking just the maximum element in magnitude.
At the bottom "out of range" or  two integer  numbers displaying the matrix elements the mouse is pointing to it.  If the number of pixels per element is at least one also the magnitude of the mouse-pointed  element is shown. On top of that the minimum and maximum of the magnitude of the elements of the original matrix are shown. These can be altered whereafter the elements outside this range are not visible anymore. On top of that the colour scale is shown.
 

Support
The support we can give on VSM is limited. Nevetheless we are interested in your comments; email to F.W.Wubs@math.rug.nl .