Thomas W. Knowles and Associates

OPTIMIZATION SPECIALISTS

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Optimization

LINDO SYSTEMS FAMILY OF OPTIMIZERS

Our firm has 40 years of experience using optimizers from Lindo Systems, Inc. There are three software packages available from Lindo Systems, Inc. We can help you choose the best alternative for your decision problem. We can also help you choose the version size and additional cost options that you need.

LINGO solves linear and nonlinear models, with continuous and/or integer variables. Two extremely useful features of LINGO are a modeling language and links to spreadsheets and databases. The modeling language allows rapid prototyping of your model. Because of the links to spreadsheets and databases, maintaining data and creating customized reports is simplified. Very often, the data resides in an Excel spreadsheet. When users can design data input formats, they are more comfortable using an optimization system. The optimized results can be exported to an Excel spreadsheet, which allows the user to design reports using Excel formulas, formatting, and macros.

The LINDO API, allows you to create your own optimization applications. You can develop your own customized applications and use the power of the LINDO optimizers. The LINDO API makes it easy for you to integrate optimization into your own application. The distribution of applications that call the LINDO API solvers requires separate licensing. The LINDO API provides you with an arsenal of powerful solvers for linear, nonlinear (convex & nonconvex), quadratic, quadratically constrained, second order cone and integer optimization. All solvers incorporate numerous enhancements for maximum speed and robustness. The other members of the Lindo Systems, Inc family of solvers, LINGO and What'sBest!, utilize the powerful LINDO API as their solvers.

What'sBest! is an add-in for Excel that brings the power of a large-scale optimizer to the spreadsheet. Like LINGO, What'sBest! solves linear and nonlinear models, with continuous and/or integer variables. Because the model resides in a spreadsheet and the optimal solution is written into it, you can use Excel’s capabilities to create your own reports.

We have much experience with developing optimization models using What’s Best!. We have observed that experienced users of Excel are not necessarily good builders of optimization models. Too often, nonlinearities are introduced by the use of Excel functions such as IF, MAX, MIN, and VLOOKUP. By doing so, you run the risk of obtaining a local optimal solution that is not the global optimal solution. We can help you avoid this!

Repeated use of a What'sBest! model to explore various decisions has its own set of problems. As you perform what-if analyses, decision cells may be changed from adjustable to fixed values. This can cause "Irreconcilable Constraints" because the fixed value may violate a constraint that has been previously created. We have developed the capability to generate constraints “on the fly” using Visual Basic for Applications (VBA). No longer will you have to worry about copying or deleting constraint formulas when you perform what-if analyses. We can create VBA routines to automate your repetitive actions and assign them to buttons so that a person who is not skilled at Excel or knowledgeable about What'sBest! can input data and print the finished reports.