EPODE

Interface facilities

In order

to create a database of method problems on which the application works (which can be seen also as a database of method examples),
to create an interface with other software products for solving differential equations;
to work on a previous saved methods,

method input/output facilities must be stipulated. It is preferable to use a general format for files; for example, we can use text files.

In order to

correct the user typing errors,
remember previous defined expressions and values,

an user-interactive, permanently ready, interface must be created. For simplification of the search procedure, the method variables, the method equations, and the procedures for starting multistep methods and for solving implicit equations, the integration values can be described in different control panels.

Example.

The user can store a defined method and reload it after some time. In this manner, a method database can be created. In EpODE's directory METHODS, one can be find approximately 100 methods for nonstiff or stiff methods, for sequential or concurrent computations. %for which an approximate solution has been calculated in test stage (a successfully solving of a problem permits to the user to save the problem, the method, the computing parameters, and the display parameters for the results in a 'Session', which can be reloaded in order to review the old results).

The item menu 'Method' conduct to the control panels for describing a new method, loading one or saving the current described one (the submenu items are; 'New method', 'Load method', 'Method equations', 'Start for multistep method', 'Start for implicit method' for 'Relationships method-Ode', 'Method properties', 'Add method to expert' in the 'Nonstiff' class of 'Stiff' class, or 'Delete from expert'). Each control panel can be accessed separately. Shortcomings are possible using the toolbar.

Variable and expression checks are made for each user-input. The input status ('Complete' or not) is also showed.

In the computer-expert mode, the user can obtain the approximate solution immediately after the problem description. The solving method is automatically selected.

After description or loading, a method can be added to the method database of the expert. In the actual version of EpODE, the user must decide by him self in which category of methods must the new method be included: methods for stiff or nonstiff problems. This decision can be take analyzing the method properties panel, more precisely the report field about the method stability. If the message 'Unbounded' was appear or a limit greater than, say 40, the method can be included in the stiff class of problems; otherwise, it is recommended to include the method in the nonstiff class of methods.

If the user have added some new methods to the method database of the expert, these methods can be deleted by activating the corresponding menu item (all added methods will be deleted, not only one). The same operation will be done by living EpODE. No registration of the new added method will be made for a future session of work with EpODE.