Build by Columns

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As noted in Build by Rows, the finished application is capable of building a model by rows or by columns, according to an option entered through the command line by the user. The next steps in this tutorial show you how to add a static method to your application to build a model by columns.

Go to the comment Step 10 in Dietlesson.cs, and add the following lines to set up your application to build the problem by columns.

   internal static void BuildModelByColumn(IMPModeler model,
                                           Data       data,
                                           INumVar[]  Buy,
                                           NumVarType type) {
      int nFoods = data.nFoods;
      int nNutrs = data.nNutrs;

Go to the comment Step 11 in Dietlesson.cs, and add the following lines to create empty columns that will hold the objective and ranged constraints of your problem.

      IObjective cost       = model.AddMinimize();
      IRange[]   constraint = new IRange[nNutrs];
    
      for (int i = 0; i < nNutrs; i++) {
         constraint[i] = model.AddRange(data.nutrMin[i], data.nutrMax[i]);
      }

Go to the comment Step 12 in Dietlesson.cs, and add the following lines to create each of the variables.

      for (int j = 0; j < nFoods; j++) {

         Column col = model.Column(cost, data.foodCost[j]);

         for (int i = 0; i < nNutrs; i++) {
            col = col.And(model.Column(constraint[i], 
                                       data.nutrPerFood[i][j]));
         }

         Buy[j] = model.NumVar(col, data.foodMin[j], data.foodMax[j], type);

      }
   }