INonLDVariables.Add

Syntax

Add(Id:String): INonLDVariable;

Parameters

Id - identifier of added variable.

Description

The Add method adds a variable to the collection.

Example

The system of non-linear equations is created in this example:

Output variables: x1, x2.
Controlling variables: u, v.
Equations that form the system:
- 0.3 * x1[t-1] + 0.1 * x2[t+1] + u[t-1] * x1[t+1] *x2[t-1].
- -0.2 * x1[t-1] + 0.4 *x2[t+1] + (x1[t+1] * x2[t-1])/(v[t-1]+1).

Sub Main;

Var

Optima: NonLinearDecomposition;

PeriodL, j, i: Integer;

Vars: INonLDVariables;

Vrbl: INonLDVariable;

RetroX1, ForestX1: Array Of Double;

RetroX2, ForestX2: Array Of Double;

RetroU, ForestU: Array Of Double;

RetroV, ForestV, InitApproximation: Array Of Double;

Funstions: Array Of String;

Res: INonLoResults;

val: Double;

Begin

Optima := New NonLinearDecomposition.Create;

// Set calculation period value

PeriodL := 4;

RetroX1 := New Double[PeriodL]; ForestX1 := New Double[PeriodL];

RetroX2 := New Double[PeriodL]; ForestX2 := New Double[PeriodL];

RetroU := New Double[PeriodL]; ForestU := New Double[PeriodL];

RetroV := New Double[PeriodL]; ForestV := New Double[PeriodL];

InitApproximation := New Double[PeriodL];

For i := 0 To PeriodL - 1 Do

RetroX1[i] := -2.1 - i; ForestX1[i] := 1.9 + i;

RetroX2[i] := -2.2 - i; ForestX2[i] := 1.8 + i;

RetroU[i] := -2.3 - i; ForestU[i] := 1.7 + i;

RetroV[i] := -2.4 - i; ForestV[i] := 1.6 + i;

InitApproximation[i] := 0.1;

End For;

// Add the first variable

Vars := Optima.Variables;

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

Vrbl.Retrospective := RetroX1;

Vrbl.CoefficientsOrderRetrospective := "x1[t];x1[t-1]";

Vrbl.Forestall := ForestX1;

Vrbl.CoefficientsOrderForestall := "x1[t];x1[t+1]";

Vrbl.InitApproximation := InitApproximation;

// Add the second variable

Vars := Optima.Variables;

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

Vrbl.Retrospective := RetroX2;

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

Vrbl.Forestall := ForestX2;

Vrbl.CoefficientsOrderForestall := "x2[t];x2[t+1]";

Vrbl.InitApproximation := InitApproximation;

// Set initial approximation to the first controlling variable

For i := 0 To PeriodL - 1 Do

InitApproximation[i] := 1.5 * (i + 1);

End For;

// Add 1-th controlling variable

Vars := Optima.Variables;

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

Vrbl.Retrospective := RetroU;

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

Vrbl.Forestall := ForestU;

Vrbl.CoefficientsOrderForestall := "u[t];u[t+1]";

Vrbl.ControlVariable := True;

Vrbl.InitApproximation := InitApproximation;

// Set initial approximation to the second controlling variable

For i := 0 To PeriodL - 1 Do

InitApproximation[i] := 2 * (i + 1);

End For;

// Add the second controlling variable

Vars := Optima.Variables;

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

Vrbl.Retrospective := RetroV;

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

Vrbl.Forestall := ForestV;

Vrbl.CoefficientsOrderForestall := "v[t];v[t+1]";

Vrbl.ControlVariable := True;

Vrbl.InitApproximation := InitApproximation;

// form system of non-linear equations

Funstions := New String[2];

Funstions[0] := "0.3 * x1[t-1] + 0.1 * x2[t+1] + 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-1])/(v[t-1]+1)";

Optima.Equations := Funstions;

Optima.NodesCount := 2;

Optima.Extremum := ExtremumType.Minimum;

Optima.MaxIteration := 250;

Optima.Tolerance := 0.000001;

Optima.MethodType := NonLinearEquationsType.HMethod;

// Calculate system

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

Debug.WriteLine(Res.ErrorMsg);

// Display results

If (Res.Status = 0) Then

Vars := Optima.Variables;

For j := 0 To Vars.Count - 1 Do

Vrbl := Vars.Item(j);

Debug.WriteLine("Variable: " + Vrbl.Id);

For i := 0 To PeriodL - 1 Do

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

Debug.WriteLine(Val);

End For;

Debug.WriteLine("-----");

End For;

End If;

End Sub Main;

After executing the example a system of non-linear equations is created and calculated. Calculation results are displayed in the console window.