static void TestHS71()
{
Console.WriteLine();
Console.WriteLine("### Test Problem: Hock-Schittkowski #71");
var problem = new OptimizationProblem();
var x1 = new Variable("x1", 1, 1, 5);
var x2 = new Variable("x2", 2, 1, 5);
var x3 = new Variable("x3", 5, 1, 5);
var x4 = new Variable("x4", 1, 1, 5);
problem.AddVariables(x1, x2, x3, x4);
problem.ObjectiveFunction = x1 * x4 * Sym.Par(x1 + x2 + x3) + x3;
problem.AddInequalityConstraints(new Constraint(x1 * x2 * x3 * x4, ConstraintComparisonOperator.GreaterThanOrEqual, 25));
problem.AddConstraints((Sym.Pow(x1, 2) + Sym.Pow(x2, 2) + Sym.Pow(x3, 2) + Sym.Pow(x4, 2)).IsEqualTo(40));
//
var solver = new IpoptSolver();
solver.OnLog += Console.WriteLine;
solver.Solve(problem);
Console.WriteLine(x1.WriteReport());
Console.WriteLine(x2.WriteReport());
Console.WriteLine(x3.WriteReport());
Console.WriteLine(x4.WriteReport());
}
public OptimizationProblem Solve(OptimizationProblem problem)
{
ipopt.Solve(problem);
return(problem);
}