(Click on the code excerpt for a full-size image.) In the last line, we call () to find the optimal solution. To do this, we define an SDK Problem object and set its properties as shown in the code excerpt below. For example, the left hand sides of the constraints are computed in NLPEvaluator_OnEvaluate(), but the constant right hand sides (5800 quarts of glue, 730 hours of pressing capacity, etc.), as well as lower bounds of 0 on the variables, must be specified separately. Next, we must tell the Solver SDK about elements of the model that aren't included in the NLPEvaluator_OnEvaluate() function above. Read Using the LP Coefficient Matrix Directly in our Advanced Tutorial for more about this option.) Using the Solver SDK Objects (In fact, we can let Solver SDK compute the objective and constraint values for us, using just the coefficients such as 450, 1150, 800 and 400 for the objective function. But we could also use Visual Basic arrays and FOR loops to compute these values. In the above code, we've written the formulas to correspond directly to our earlier outline of the problem (click on Writing the Formulas to see this again). In the VB.NET code excerpt below, we define a function NLPEvaluator_OnEvaluate() that accesses elements of the model through Solver SDK objects. Call the Optimize() method in your program to find the optimal solution.Īssuming that you have Visual Studio and Solver Platform SDK installed, and you've opened a new or existing project, the next step is to define a VB.NET function where the formulas for the objective function and the constraints are calculated.Use SDK objects in your program to tell the Solver about your decision variables, objective and constraint calculations, and desired bounds on constraints and variables.Similarly, create assignment statements in your program to calculate the left hand sides of your constraints.
Create an assignment statement in your program, that calculates the objective function in your model.Create a variable in your program to hold the value of each decision variable in your model.NET program (the steps in another Windows programming language would be very similar): Follow these steps to define and solve the Product Mix problem in a Visual Basic.
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