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Program appearance and Controls



In the top left-hand corner of the main xrk window, there is a menu bar with three headings, File, Change, and Task. Clicking MB1 on one of these headings pops up an associated menu. Entries on these menus allow you to read and save data files, change models, change parameters, and compute the time average of the solution. Brief descriptions of what each menu entry does appear in this section.

Menu dialog boxes

Nearly all of the menu entries pop up a dialog box that the user intracts with to further specify the action to be taken. For example, when a menu item for reading in a data file is selected, a file selection dialog box pops up which allows the user to select the file to be loaded. In the xrk program there are four different types of dialog boxes that pop up when various menu items are selected. These four types are described below. The only other type of dialog box the user will encounter is a warning message box, which is also described briefly below.

List selection box
This dialog box contains a list. One of the items in the list must be selected with MB1. An alternative is to type the name of one of the items in the list in the Selection text field. The name typed in must match one of the items in the list or an error occurs.

File selection box
This is the standard Motif file selection dialog box. It allows the user to select a file for loading, or to name a file to be saved. A file name is selected by by clicking MB1 on one of the items in the Files list which appears in the middle of the dialog, to the right of the Directories list. Moving around in the file system can be accomplished either by double-clicking MB1 on directories in the Directories list to move up or down, or typing in a suitable filter string in the Filter text window and clicking MB1 on the Filter button. To name a file for saving, type the file name in the Selection window. Once you have selected or named a file, click on the OK button to initiate the read or save. If a problem occurs, a Message dialog will pop up describing the situation.

Parameter change box
This dialog allows the user to change the values of various program parameters. The upper part contains one or more label-text field pairs. The lower part contains three push buttons labeled OK, Apply, and Cancel.

The value of the parameter referred to by one of the labels can be changed by editing the value in the corresponding text field. Note that changes to the parameter values in the program do not occur until the OK or Apply button is pressed. If the OK button is pressed, the parameter values are changed and the dialog disappears. If the Apply button is pressed, the changes are made but the dialog does not disappear. This is convenient if a series of changes are to be made or if the user wants to keep the current values displayed.

The numbers in the text fields are expected to be in decimal or scientific notation format. If an attempt is made to enter an improperly formatted value, a warning message box appears and the change is not made. In certain specific cases described below, there are restrictions on the values that parameters can have. If the changes requested cannot be made a warning message box describing the problem appears.

Parameter display box
This is not really a dialog, because the user can't interact with it. It pops up if the time averaged solution is being computed and displays the values of the time averaged solution.

Warning message box
This dialog warns the user of potential problems. It consists of a warning message and a single Acknowledge push button.

File menu

The File menu provides the interface to the commands for saving and reading data files and also quitting the program. The data file formats are described in detail in the section on file formats. Besides providing input for the xpde program, the data files can be used with other programs to generate plots suitable for publication. For example, the Maple program dataplot for plotting snapshot files is available at WPI.

Change menu

Several of these entries pop up parameter change dialogs that can be kept on the screen by using the Apply button instead of the OK button.

Task menu

Allows the user to change certain aspects of how xrk behaves.

Control panel


Briefly, the control panel is intended to provide the user with information on the current model, including the name of the model, the values of the most recent initial condition, and values of the model parameters. It also provides the program interface for starting and stopping integration, clearing the display window, displaying and resetting the elapsed time, and changing the values of the initial conditions and model parameters. This section describes in detail all of the components in the control panel.

Model identification

The top part of the control panel contains one label-text field pair. The entry in the text field identifies the name of the current model. The text field is not editable. It can be changed only via the Model entry in the Change menu. Selecting this menu items pops up a list selection box, giving a list of models to choose from.

Most recent initial conditions

This region consists of a label Variables, N label-text field pairs, where N is the number of components in the model, and a push button, labeled Set Variables. To change the initial conditions, just edit the entries in the text fields and then click MB1 on the Set Variables push button to actually make the changes take effect. An alternative to typing is to just click in the plot window(s) on the locations of the desired initial conditions. Again, the changes don't take effect until the Set Variables button is pushed.

If you change to a model with a different number of components, the number of label-text field pairs will also change. The entries in the label part of each label-text field pair are specified as part of the process of adding the model to xpde. This process is not explained in this document, but it is relatively easy to do by eding two files and recompiling.

Either decimal or scientific notation must be used for the initial condition text field entries. That is, the program would accept either ``0.0002'' or ``2.e-04'' as representing the same number. The program checks to make sure that the entry adheres to one of these formats. An entry like ``e-01'' would not be accepted. However, note that an entry like ``1/400'' would be accepted, but the value of the diffusion coefficient would be set to 1, not 0.0025, due to the way the C language works.

Model parameters

Below the initial condition region of the control panel is a region for displaying and setting the values of the model parameters. It is very similar in appearance and operation to the inital condition region described above. To change the values of model parameters, edit the values in the text fields and then click MB1 on the Set Parameters push button.

Starting and Stopping

At the bottom of the control panel is a region with four push buttons and a label-text field pair. The text field displays the time elapsed since the it was last reset. The elapsed time is reset to zero when the user selects a different model or when the Reset Time button is pushed. It is not reset when the Stop button is pushed.

The user can control how frequently the time display is updated by changing the value of the Time update parameter via the Step information item in the Change menu. Several other program parameters affecting solution discretization and display are also available via this same menu item; for details see the previous section on menus.

The functions of the four push buttons are as follows.

Plot window(s)

Plot window(s) display the solution components as they are computed. The present version of xpde is limited to models with an even number tex2html_wrap_inline1389 of components.

The part of the graph of the solutions which actually appears in the display window is determined by the values of the maximum and minimum ordinate and abscissa values in the program. These values can be changed via the Plot ranges item in the Change menu. There is presently no provision for displaying coordinate axes in the plot windows or of changing the plot ranges of individual windows.

next up previous
Next: File formats Previous: Tutorial

William W. Farr
Fri Oct 25 13:53:45 EDT 1996