What'sBest!

Excel Add-in for large-scale Linear, Nonlinear, and Mixed Integer programming

What'sBest! is an add-in to Excel that allows optimization models to be built in a free form layout within the spreadsheet environment. The linear, integer, and nonlinear solvers in What'sBest! have been designed for large scale commercial use and field tested on real-world models by companies around the world. For optimization modeling in Excel, What'sBest! provides excellent speed and substantial capacity.

Primal and Dual Simplex Solvers

The base version includes the Primal and Dual Simplex solvers, which incorporate numerous enhancements for maximum speed and robustness.

Barrier Solver

The optional Barrier solver provides an alternative means of solving linear models. The Barrier option utilizes a barrier or interior point method to solve linear models. Depending upon the size and structure of a particular model, the Barrier solver may be significantly faster than the Simplex solvers and can provide exceptional speed on large linear models.

Preprocessing routines are available with all three What'sBest! linear solvers. Scaling procedures can improve speed and robustness on numerically difficult models. Model reduction techniques can often make models solve faster by analyzing the original formulation and mathematically condensing it into a smaller problem.

Nonlinear Solver

For nonlinear programming models, the primary underlying technique used by What'sBest!'s optional nonlinear solver is based upon a Generalized Reduction Gradient (GRG) algorithm. The nonlinear solver takes advantage of sparsity for improved speed and more efficient memory usage. It also offers a variety of algorithmic options including a Crash procedure, a Steepest Edge/Steepest Decent option, and Sequential Linear Programming prodecures. What'sBest! will automatically select the solution approach that appears best suited to the specific model at hand. The solution approach is dynamically adjusted during the solution process based upon the model's behavior.

Integer Solver

For models with general and binary integer restrictions, What'sBest! includes an integer solver that works in conjunction with the linear and nonlinear solvers. For linear models, the integer solver does extensive preprocessing and adds constraint "cuts" of several different varieties to greatly improve solution times on large classes of integer models.

Intelligent Integration

What'sBest! is seamlessly integrated into Excel making it a natural extension of the spreadsheet environment. It handles the details of the solution process, so you can focus on modeling. When the Solve command is initiated, What'sBest! analyzes the problem and, when possible, reduces the problem and even substitutes out variables. With What'sBest!, you never have to specify whether to use the linear or nonlinear solver. Based upon the model's structure, What'sBest! automatically selects the appropriate solver and intelligently adjusts internal parameters.

What'sBest! is an excellent tool for creating optimization applications for use by others. What'sBest! allows model developers to provide an application to a manager or client in an environment that is familiar to most computer users.

What'sBest! comes with a comprehensive User's Manual that describes the commands and features of the program. Also included in the manual is discussion of the major classes of linear, integer, and nonlinear optimization problems along with over two dozen real-world based examples.

A free trial version of What'sBest! is available from the LINDO Systems website. It has all of the functions and features of our regular version, but the problem capacity has been limited.

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