New features in DFIELD and PPLANE for MATLAB version 4.2

These changes have been class tested and should be quite stable.

New features as of September 23, 1996.

The Systems Menu in PPLANE

In the PPLANE Setup window there is now a Systems menu. The purpose of the menu is to allow the user to save PPLANE systems as disk files, and then to load them from the disk later. A PPLANE system file contains all of the information about a system that is displayed on the PPLANE Setup window, including the dimensions of the display window, and the description of the field to be displayed.

The menu contains three options.

Error Trapping

The purpose here was to trap as many data entry errors as possible in DFIELD and PPLANE, and to provide specific and informative error messages to the user in place of the standard MATLAB error messages. As a result the programs should be much more user friendly. In addition DFIELD and PPLANE are left in a condition where the user can continue to use them, instead of having to quit and start over, as was so often the case previously.

I have no doubt that there are still some data entry errors that will give rise to MATLAB error messages instead of the more specific messages I am able to provide. If a user can replicate such an error I want to know about it. Please send me email.

New features as of September 24, 1995.

I have made three changes to DFIELD and PPLANE to date.

A New Zoomback Option

Students have long been asking for an easy way to undo zooming. I finally thought of a very good way to do this.

All Windows Are Now Resizable

This is the way things should have always been. The size can be adjusted, for example, to allow type size that is a little too big to fit properly.

The Default Sizes Of All Windows Can Be Changed

This can be done by defining global variables in the Command Window. Perhaps this is not too exciting --- unless you are using a computer in class and want to use large figures and large print. At Rice we use this feature together with the resizable windows to customize dfield and pplane for this purpose.

The variables and the windows they control are:


   DFSETPOS             % The Setup window
   DFKBDPOS             % The Keyboard entry window
   DFZOOMBACKPOS        % The Zoomback window
   DFSETTINGSPOS        % The Settings window


   PPSETPOS             % The Setup window
   PPKBDPOS             % The Keyboard entry window
   PPZOOMBACKPOS        % The Zoomback window
   PPSETTINGSPOS        % The Settings window
   PPEQPTPOS            % The Equilibrium point data window
   PPXYPOS              % The Graph window
Each of the global variables must be a four vector of the form
             [left, bottom, width, height].
The units are pixels. The fist two define the lower left corner of the window, measured from the lower left corner of the screen. The other two define the size of the window.

The easy way to determine these variables is to let MATLAB do it. Here's how. Open the window of your choice, and use the resizable feature to give it the size and position you want. Then the command

will give you the required position vector.

For example, if your favorite postion for the PPLANE Setup Window is

               >> get(gcf,'pos')
               ans = 

                   286    93   778   549
Then entering
               >> global PPSETPOS
               >> PPSETPOS = [286, 93, 778, 549];
will result in the window opening in that position every time during the current session.

To get the new default positions without having to enter them each time you start up MATLAB, enter them in your startup.m file.

This page is maintained by John C. Polking,
Last modified: Tue May 27 17:34:01 CDT 1997