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NOTE   You can click the Help button in the dialog box to get more information about other options.

  1. In the Solver Parameters dialog box, click Options.
  2. In the Solver Options dialog box, on the Evolutionary tab, choose one or more of the following options:


  • In the Convergence box, type the maximum percentage difference in objective values for the top 99% of the population that Solver should allow in order to stop with the message “Solver converged to the current solution.” Smaller values here normally mean that Solver will take more time, but will stop at a point closer to the optimal solution.

Mutation Rate

  • In the Mutation Rate box, type a number between 0 and 1, the relative frequency with which some member of the population will be altered or “mutated” to create a new trial solution, during each “generation” or subproblem considered by the Evolutionary method. A higher Mutation Rate increases the diversity of the population and the chance that a new, better solution will be found; but this may increase total solution time.

Population Size

  • In the Population Size box, type the number of different points (values for the decision variables) you want the Evolutionary method to maintain at any given time in its population of candidate solutions. The minimum population size is 10 members; if you supply a value less than 10 in this box, or leave it blank, the Evolutionary Solver uses a population size of 10 times the number of decision variables in the problem, but no more than 200.

Random Seed

  • In the Random Seed box, type a positive integer number to be used as the (fixed) seed for the random number generator used for a variety of random choices in the Evolutionary method. If you enter a number here, the Evolutionary method will use the same choices each time you click Solve. If you leave this box blank, the random number generator will use a different seed each time you click Solve, which may yield a different (better or worse) final solution.

Maximum Time without Improvement

  • In the Maximum Time without Improvement box, type the maximum number of seconds you want the Evolutionary method to continue without a meaningful improvement in the objective value of the best solution in the population, before it stops with the message “Solver cannot improve the current solution.

Require Bounds on Variables

  • Select the Require Bounds on Variables check box to specify that the Evolutionary method should run only if you have defined lower and upper bounds on all decision variables in the Constraints list box. The Evolutionary method is far more effective if you define bounds on all variables; the tighter the bounds on the variables that you can specify, the better the Evolutionary method is likely to perform.

NOTE You can click the Help button in the dialog box to get more information about other options.