Try our new documentation site (beta).

Filter Content By
Version

### qp_c++.cpp

/* Copyright 2016, Gurobi Optimization, Inc. */

/* 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

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");

// Integrate new variables

model.update();

// 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;
}


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

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.
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.