Try our new documentation site.


qp_c++.cpp


/* Copyright 2019, Gurobi Optimization, LLC */

/* This example formulates and solves the following simple QP model:

     minimize    x^2 + x*y + y^2 + y*z + z^2 + 2 x
     subject to  x + 2 y + 3 z >= 4
                 x +   y       >= 1
                 x, y, z non-negative

   It solves it once as a continuous model, and once as an integer model.
*/

#include "gurobi_c++.h"
using namespace std;

int
main(int   argc,
     char *argv[])
{
  try {
    GRBEnv env = GRBEnv();

    GRBModel model = GRBModel(env);

    // Create variables

    GRBVar x = model.addVar(0.0, 1.0, 0.0, GRB_CONTINUOUS, "x");
    GRBVar y = model.addVar(0.0, 1.0, 0.0, GRB_CONTINUOUS, "y");
    GRBVar z = model.addVar(0.0, 1.0, 0.0, GRB_CONTINUOUS, "z");

    // Set objective

    GRBQuadExpr obj = x*x + x*y + y*y + y*z + z*z + 2*x;
    model.setObjective(obj);

    // Add constraint: x + 2 y + 3 z >= 4

    model.addConstr(x + 2 * y + 3 * z >= 4, "c0");

    // Add constraint: x + y >= 1

    model.addConstr(x + y >= 1, "c1");

    // Optimize model

    model.optimize();

    cout << x.get(GRB_StringAttr_VarName) << " "
         << x.get(GRB_DoubleAttr_X) << endl;
    cout << y.get(GRB_StringAttr_VarName) << " "
         << y.get(GRB_DoubleAttr_X) << endl;
    cout << z.get(GRB_StringAttr_VarName) << " "
         << z.get(GRB_DoubleAttr_X) << endl;

    cout << "Obj: " << model.get(GRB_DoubleAttr_ObjVal) << endl;

    // Change variable types to integer

    x.set(GRB_CharAttr_VType, GRB_INTEGER);
    y.set(GRB_CharAttr_VType, GRB_INTEGER);
    z.set(GRB_CharAttr_VType, GRB_INTEGER);

    // Optimize model

    model.optimize();

    cout << x.get(GRB_StringAttr_VarName) << " "
         << x.get(GRB_DoubleAttr_X) << endl;
    cout << y.get(GRB_StringAttr_VarName) << " "
         << y.get(GRB_DoubleAttr_X) << endl;
    cout << z.get(GRB_StringAttr_VarName) << " "
         << z.get(GRB_DoubleAttr_X) << endl;

    cout << "Obj: " << model.get(GRB_DoubleAttr_ObjVal) << endl;

  } catch(GRBException e) {
    cout << "Error code = " << e.getErrorCode() << endl;
    cout << e.getMessage() << endl;
  } catch(...) {
    cout << "Exception during optimization" << endl;
  }

  return 0;
}

Try Gurobi for Free

Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.

Evaluation License
Get a free, full-featured license of the Gurobi Optimizer to experience the performance, support, benchmarking and tuning services we provide as part of our product offering.
Academic License
Gurobi supports the teaching and use of optimization within academic institutions. We offer free, full-featured copies of Gurobi for use in class, and for research.
Cloud Trial

Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.

Search