INonLoConstraint.Expression

Syntax

Expression: String;

Description

The Expression property determines a constraint function.

Example

Sub Main;

Var

Optima: NonLinearOptimization;

Vars: INonLoVariables; //list of variables

Vrbl: INonLoVariable; //variable

VarConstr: IVarConstraint; //variable constraint

VarConstrs: IVarConstraints; //list of variable constraints

Constraints: INonLoConstraints; //list of constraints

Constraint: INonLoConstraint; //constraint

RetroX1: Array[3] Of Double;

RetroX2: Array[3] Of Double;

RetroU: Array[3] Of Double;

RetroV: Array[3] Of Double;

Funstions: Array[2] Of String;

Res: INonLoResults;

TimeInterval: Integer;

s: String;

ci: ICultureInfo;

j, i: Integer;

val: Double;

Begin

Optima := New NonLinearOptimization.Create;

RetroX1[0] := 2;

RetroX1[1] := 2.1;

RetroX1[2] := 2.2;

RetroX2[0] := 1;

RetroX2[1] := 0.9;

RetroX2[2] := 0;

RetroU[0] := 1;

RetroU[1] := 1.5;

RetroU[2] := 0;

RetroV[0] := 0.5;

RetroV[1] := 0.75;

RetroV[2] := 0;

// VARIABLES and constraints

Vars := Optima.Variables;

Vrbl := Vars.Add("x1");

Vrbl.Retrospective := RetroX1;

Vrbl.CoefficientsOrder := "x1[t];x1[t-1];x1[t-2];;x1[t-3]";

VarConstrs := Vrbl.Constraints;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -101;

VarConstr.UpperBound := 101;

VarConstr.Lag := 3;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -102;

VarConstr.UpperBound := 102;

VarConstr.Lag := 2;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -10030;

VarConstr.UpperBound := 10030;

VarConstr.Lag := 1;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -13040;

VarConstr.UpperBound := 13040;

VarConstr.Lag := 0;

Vars := Optima.Variables;

Vrbl := Vars.Add("x2");

Vrbl.Retrospective := RetroX2;

Vrbl.CoefficientsOrder := "x2[t];x2[t-1];x2[t-2]";

VarConstrs := Vrbl.Constraints;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -201;

VarConstr.UpperBound := 201;

VarConstr.Lag := 3;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -202;

VarConstr.UpperBound := 202;

VarConstr.Lag := 2;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -203;

VarConstr.UpperBound := 203;

VarConstr.Lag := 1;

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := -12040;

VarConstr.UpperBound := 12040;

VarConstr.Lag := 0;

//Controlling variable

Vars := Optima.Variables;

Vrbl := Vars.Add("u");

Vrbl.Retrospective := RetroU;

Vrbl.ControlVariable := True;

Vrbl.CoefficientsOrder := "u[t];u[t-1]";

VarConstrs := Vrbl.Constraints;

For i := 0 To 3 Do

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := 0;

VarConstr.UpperBound := 1;

VarConstr.Lag := i;

End For;

//Controlling variable

Vars := Optima.Variables;

Vrbl := Vars.Add("v");

Vrbl.Retrospective := RetroV;

Vrbl.ControlVariable := True;

Vrbl.CoefficientsOrder := "v[t];v[t-1]";

VarConstrs := Vrbl.Constraints;

For i := 0 To 3 Do

VarConstr := VarConstrs.Add;

VarConstr.LowerBound := 0.8;

VarConstr.UpperBound := 4;

VarConstr.Lag := i;

End For;

Funstions := New string[2];

Funstions[0] := "0.3 * x1[t-1] + 0.1 * x2[t-2] + u[t-1] * x1[t-1] *x2[t-1]";

Funstions[1] := "-0.2 * x1[t-1] + 0.4 *x2[t-1] + (x1[t-1] * x2[t-2])/v[t-1]";

Optima.Equations := Funstions;

Optima.CriterionFunction := "x1[t] * x1[t] - x1[t] * x2[t]";

Constraints := Optima.Constraints;

Constraint := Constraints.Add;

Constraint.LowerBound := "3";

Constraint.UpperBound := "200";

Constraint.Expression := " x1[t] + x2[t]";

TimeInterval := 4;

Optima.NodesCount := 2;

Optima.MaxIterationsCount := 1500;

Optima.MethodType := CpNonLinearMethodType.SequentialQP;

Optima.Tolerance := 0.0001;

Optima.Extremum := ExtremumType.Maximum;

Res := Optima.Evaluate(TimeInterval) As INonLoResults;

s := "Optimal value: " + Res.OptimalValue.ToString;

Debug.WriteLine(s);

s := "     ";

For j := 1 To Vars.Count Do

Vrbl := Vars.Item(j - 1);

s := s + Vrbl.Id + "        ";

End For;

Debug.WriteLine(s);

ci := CultureInfo.Current;

For i := 1 To TimeInterval Do

s := "t=" + i.ToString + ", ";

For j := 1 To Vars.Count Do

Vrbl := Vars.Item(j - 1);

Val := Res.VarValues(Vrbl.Id)[i - 1];

s := s + ci.FormatDoublePrec(Val, 6) + ", ";

End For;

Debug.WriteLine(s);

End For;

s := "Status : " + Res.Status.ToString;

Debug.WriteLine(s);

s := "Error : " + Res.ErrorMsg;

Debug.WriteLine(s);

End Sub Main;

After executing the example the console window displays calculation results.

See also:

INonLoConstraint