Modeling and Optimization Systems

Visual XPRESS Authors: Dash Associates Ltd
Blisworth House
Church Lane
Northants NN7 3BX, UK
Tel: +44 1604 858993 Fax: +44 1604 858147
Description Visual XPRESS (previously known as XPRESS-MP for Windows) is Dash's new look for modelling and optimisation software. Building on the world's most productive modelling system and the fastest Linear and Integer Programming optimiser, Visual XPRESS gives you a comfortable environment and the familiar look and feel of Microsoft Windows. Ideal for the novice and student user, Visual XPRESS really comes into its own for the system builder who needs to experiment with various modelling and optimisation strategies. The full power of the modeller and optimiser features are available, along with an intelligent editor and context sensitive on-line help system. With Visual XPRESS you can be more productive, and provide your users with the solutions they need in record time.
Visual XPRESS features include: A Text Editor Editing your model files is done from within Visual XPRESS. Just click on an error message for help or to go to the error. Edit several models simultaneously, cutting and pasting between them.
Keyword Insertion A pop-up menu allows you to insert keywords into model files and even gives an optional syntax reminder.
A Context-Sensitive Help System Help is always readily available. The user interface, modelling keywords, modeller options and optimiser options are all included in a hyper-text environment, cross-referencing related topics and keywords. Existing XPRESS-MP DOS users will find that Dash's DOS Dinosaur will answer all their conversion queries.
A Database to Store your Options for each Problem Each of your problems has its own set of modelling and optimising controls and parameters. Visual XPRESS incorporates a database that stores all these controls and parameters, letting you get on with writing and debugging your models.
Easy Access to the Modeller and Optimiser Access to the modeller and optimiser is through menu selections and dialog boxes. All of your controls and parameters are checked as they are input and any invalid entries are immediately corrected.
The XPRESS-MP Subroutine Libraries The XPRESS-MP modeller and optimisers are available as subroutine libraries which can be linked directly into end-user applications. The XPRESS-MP Optimiser Subroutine Library (XOSL) has two levels. The Level 1 subroutine library consists of the equivalents of mp-opt calls such as input, minim and fprint. It is particularly easy to use. The Level 2 subroutine library has a much richer functionality. With the level 2 routines, matrices can be created entirely within a C, C++ or FORTRAN program and passed to the XPRESS optimiser; the matrices can be optimised and the optimal solution obtained from the XPRESS internal data structures. Extra rows and columns can be added to the matrix and existing rows and columns can be deleted or changed before re-optimising the problem. With the XPRESS-MP Modeller Subroutine Library (XMSL) a user can embed matrix generation within a high level language, for a totally integrated solution. XOSL and XMSL are available on DOS and UNIX platforms and as Microsoft Windows Dynamic Link Libraries, where they can be called from FORTRAN, C, C++, Visual Basic or any other language supporting DLL calls. Comprehensive structured documentation and Dash's famed hot-line support will speed your path to working optimisation systems.
Dynamic Link Libraries for Windows Dash's XPRESS-MP model builder and optimiser are available as DLLs. Both DLLs let you access the various features and functions of the optimiser or model builder via any programming language compatible with Windows. For instance, the DLLs might be called from C, C++, Visual Basic, Excel or Access. This is an essential facility for users who want to embed XPRESS in a larger system and enables the developer to restrict user access to the XPRESS modules if desired. The ability to incorporate the modeller and optimiser also allows XPRESS to be built into a customised software design such as a database or spreadsheet with optimisation capabilities.
References Josef Kallrath and John M. Wilson, Business Optimisation Using Mathematical Programming, Macmillan 1997, ISBN 0-333-67623-8 H. P. Williams, Model Building in Mathematical Programming Third Edition Revised, Faculty of Mathematical Studies, University of Southampton, UK, Wiley, 1993, ISBN 0471 94111 5