ISmNonLinearEquations.DerivativeShift

Syntax

DerivativeShift: Double;

Description

The DerivativeShift property determines the increment of an argument (%) for calculating partial derivatives required for the Newton method.

Example

Sub Main;

Var

Eqs: ISmNonLinearEquations;

Funcs: Array [0..2] Of String;

inits: Array[0..2] Of Double;

res: Integer;

Sub Print(Data: Array Of Double);

Var

i: Integer;

CI: ICultureInfo;

Begin

CI := CultureInfo.Current;

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

For i := 0 To Data.Length - 1 Do

If Double.IsNan(Data[i]) Then

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

Else

Debug.WriteLine(i.ToString + ", " + CI.FormatDoublePrec(Data[i], 4));

End If;

End For;

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

End Sub Print;

Begin

Eqs := New SmNonLinearEquations.Create As ISmNonLinearEquations;

funcs[0] := "X1-22+0.5*X2-X3";

funcs[1] := "X2-26.5+2*X1+0.5*X3";

funcs[2] := "X3+9-X1+6*X2";

Eqs.Functions := Funcs;

Eqs.CoefficientsOrder := "X1;X2;X3";

inits[0] := 10; //x1

inits[1] := 0; //x2

inits[2] := -1; //x3

Eqs.InitApproximation := inits;

Eqs.MethodType := NonLinearEquationsType.NewtonMethod;

Eqs.DerivativeShift := 0.6;

res := Eqs.Execute;

If res <> 0 Then

Debug.WriteLine(Eqs.Errors);

Else

Print(Eqs.Solution);

End If;

End Sub Main;

After executing the example the console window displays a solution for a system of non-linear equations:

Module execution started

---Begin---

0, 14.0000

1, 2.0000

2, -7.0000

---End---

Module execution finished