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Building GUIs with Tcl/Tk - A GUI front-end to NAG Fortran Library Example Programs

The main purpose of this article is to demonstrate that Tcl/Tk provides a very convenient environment to build fairly robust GUIs. (For a brief introduction to Tcl/Tk, see an earlier article by the author in Graphics and Visualization Newsletter No. 40) In this article, by way of example, a simple GUI front-end is presented to collection of example programs supplied with NAG Fortran library software.

Typically, a novice user of the library can copy the example programs and input data, compile, link and run the resulting executables. This command line interaction offers very little scope to browse through other examples and experiment. The above activities can be neatly packaged into a convenient GUI using Tcl/Tk, thereby providing the user with ample scope to browse and experiment much more fluently.

NAG F77 Library is divided into several chapters each dealing with a well defined area of numerical computation. (For example, subroutines dealing with numerical integration are included in the Chapter entitled Quadrature). The proposed GUI closely mimics the organization of the library, and fully exploits the naming conventions used for the subroutines. All the required information used in various windows is discerned from the documentation supplied with the library software, which makes the front-end virtually maintenance free!

The GUI consists of three main components: a startup window which presents a list of available chapters in the library; a chapter level window displaying the available routines; and finally a routine level window in which the user can interact with a chosen example program for the routine. The startup window also implements a simple hypertext facility to explore Essential Introduction to the library. Help is also provided on replaced routines and nag-to-blas-lapack equivalent names. Readers interested in obtaining a copy of the program, please contact the author by sending an e-mail to

Dr Venkat V S S Sastry
Applied Mathematics and Operational Research Group
Royal Military College of Science, Shrivenham, Wilts SN6 8LA

Tel: +44 1793 785315
Fax: +44 1793 784196