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Problem-Based Workflow


There are two different Optimization Toolbox™ approaches for solving linear programming, mixed-integer linear programming, and quadratic programming problems. This section describes the problem-based approach. Solver-Based Optimization Problem Setup describes the solver-based approach.

To solve a problem with linear or quadratic objective function and linear constraints, perform the following steps.

  • Create a problem object by using optimproblem. A problem object is a container that you fill with objective and constraint expressions. These expressions define the problem, along with bounds that exist in the problem variables.

    For example, create a maximization problem.

    prob = optimproblem('ObjectiveSense','maximize');
  • Create named variables by using optimvar. An optimization variable is a symbolic variable that you use to describe the problem objective and constraints. Include any bounds in the variable definitions.

    For example, create a 15-by-3 array of binary variables named 'x'.

    x = optimvar('x',15,3,'Type','integer','LowerBound',0,'UpperBound',1);
  • Define the objective function in the problem object as an expression in the named variables.

    For example, assume that you have a real matrix f of the same size as a matrix of variables x, and the objective is the sum of the entries in f times the corresponding variables x.

    prob.Objective = sum(sum(f.*x));
  • Define constraints in the problem object as expressions in the named variables.

    For example, assume that the sum of the variables in each row of x must be one, and the sum of the variables in each column must be no more than one.

    onesum = sum(x,2) == 1;
    vertsum = sum(x,1) <= 1;
    prob.Constraints.onesum = onesum;
    prob.Constraints.vertsum = vertsum;
  • Solve the optimization problem by using solve.

    sol = solve(prob);

In addition to these basic steps, you can review the problem definition before solving the problem by using showproblem and related functions. Set options for solve by using optimoptions, as explained in Change Default Solver or Options.

For a basic example, see Mixed-Integer Linear Programming Basics: Problem-Based or the video version Solve a Mixed-Integer Linear Programming Problem using Optimization Modeling. For larger, scalable examples, see Factory, Warehouse, Sales Allocation Model: Problem-Based, Traveling Salesman Problem: Problem-Based, or other examples in Linear Programming and Mixed-Integer Linear Programming or Quadratic Programming.

See Also

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