Type: Integer, Input Default Value: 3 Description: Solver options 0 = Benchmark All Solvers 1-5 = Available Solvers Depends on License

SOLVER selects the solver to use in an attempt to find a solution. There are free solvers: 1: APOPT, 2: BPOPT, 3: IPOPT distributed with the public version of the software. There are additional solvers that are not included with the public version and require a commercial license. IPOPT is generally the best for problems with large numbers of degrees of freedom or when starting without a good initial guess. BPOPT has been found to be the best for systems biology applications. APOPT is generally the best when warm-starting from a prior solution or when the number of degrees of freedom (Number of Variables - Number of Equations) is less than 2000. APOPT is also the only solver that handles Mixed Integer problems. Use option 0 to compare all available solvers.

Options for solvers can be set using configuration parameters such as MAX_ITER or else by creating an options file such as **ipopt.opt** or **apopt.opt**. Below is an example of setting options for the APOPT solver for a mixed integer nonlinear programming solution. The *File...End File* section creates a new **apopt.opt** file when APMonitor compiles the model file.

File apopt.opt minlp_maximum_iterations 10000 minlp_max_iter_with_int_sol 500 minlp_as_nlp 1 minlp_branch_method 3 minlp_gap_tol 1.0e-2 minlp_integer_tol 1.0e-2 minlp_integer_max 2.0e9 minlp_integer_leaves 1 minlp_print_level 1 nlp_maximum_iterations 500 objective_convergence_tolerance 1.0e-6 constraint_convergence_tolerance 1.0e-6 End File

Refer to Options for apopt.opt for additional details for the **APOPT** solver and Options for ipopt.opt for additional details for the **IPOPT** solver.

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Page last modified on September 04, 2017, at 12:34 PM