Newton Raphson not working

[spranto]

Hi guys I allready oppened another thread to know if someone can help me to solve a 3 non linear equation system. I tryed this code to make the newton raphson method to work, but insted of converging it is diverging. Can someone please help me? Thank's!

'Cálculo do Sistema para obter os cossenos directores através do método Newton-Raphson
 
        Dim nr, aux1, aux2, aux3, lll, mmm, nnn, ff, gg, hh, ite As Double
 
        'Condição inicial l=m=n=1
        lll = 0.5
        mmm = 0.5
        nnn = 0.5
 
        'For nr = 0 To 2
        For ite = 0 To 20
 
            Dim Gauss As New GaussJ
            Gauss.InpNumEq = 3
 
            Gauss.ManagMat(0, 0) = y(0, 0) - aux(2)
            Gauss.ManagMat(0, 1) = y(0, 1)
            Gauss.ManagMat(0, 2) = y(0, 2)
            Gauss.ManagMat(1, 0) = y(1, 0)
            Gauss.ManagMat(1, 1) = y(1, 1) - aux(2)
            Gauss.ManagMat(1, 2) = y(1, 2)
            Gauss.ManagMat(2, 0) = 2 * lll
            Gauss.ManagMat(2, 1) = 2 * mmm
            Gauss.ManagMat(2, 2) = 2 * nnn
 
            'f(l,m,n)
 
            ff = (y(0, 0) - aux(2)) * lll + y(0, 1) * mmm + y(0, 2) * nnn
            gg = y(1, 0) + (y(1, 1) - aux(2)) + y(1, 2)
            hh = lll ^ 2 + mmm ^ 2 + nnn ^ 2 - 1
 
            Gauss.ManagCons(0) = -ff
            Gauss.ManagCons(1) = -gg
            Gauss.ManagCons(2) = -hh
 
            Gauss.gaussj()
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x1= " & Format(Gauss.ManagCons(0), "0.0000")
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x2= " & Format(Gauss.ManagCons(1), "0.0000")
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x3= " & Format(Gauss.ManagCons(2), "0.0000")
 
            lll = Gauss.ManagCons(0) + lll
            mmm = Gauss.ManagCons(1) + mmm
            nnn = Gauss.ManagCons(2) + nnn
 
 
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "l=" & lll
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "m=" & mmm
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "n=" & nnn
        Next ite
        ' Next nr
 

[Dököll]

Hi guys I allready oppened another thread to know if someone can help me to solve a 3 non linear equation system. I tryed this code to make the newton raphson method to work, but insted of converging it is diverging. Can someone please help me? Thank's!

'Cálculo do Sistema para obter os cossenos directores através do método Newton-Raphson
 
        Dim nr, aux1, aux2, aux3, lll, mmm, nnn, ff, gg, hh, ite As Double
 
        'Condição inicial l=m=n=1
        lll = 0.5
        mmm = 0.5
        nnn = 0.5
 
        'For nr = 0 To 2
        For ite = 0 To 20
 
            Dim Gauss As New GaussJ
            Gauss.InpNumEq = 3
 
            Gauss.ManagMat(0, 0) = y(0, 0) - aux(2)
            Gauss.ManagMat(0, 1) = y(0, 1)
            Gauss.ManagMat(0, 2) = y(0, 2)
            Gauss.ManagMat(1, 0) = y(1, 0)
            Gauss.ManagMat(1, 1) = y(1, 1) - aux(2)
            Gauss.ManagMat(1, 2) = y(1, 2)
            Gauss.ManagMat(2, 0) = 2 * lll
            Gauss.ManagMat(2, 1) = 2 * mmm
            Gauss.ManagMat(2, 2) = 2 * nnn
 
            'f(l,m,n)
 
            ff = (y(0, 0) - aux(2)) * lll + y(0, 1) * mmm + y(0, 2) * nnn
            gg = y(1, 0) + (y(1, 1) - aux(2)) + y(1, 2)
            hh = lll ^ 2 + mmm ^ 2 + nnn ^ 2 - 1
 
            Gauss.ManagCons(0) = -ff
            Gauss.ManagCons(1) = -gg
            Gauss.ManagCons(2) = -hh
 
            Gauss.gaussj()
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x1= " & Format(Gauss.ManagCons(0), "0.0000")
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x2= " & Format(Gauss.ManagCons(1), "0.0000")
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "******x3= " & Format(Gauss.ManagCons(2), "0.0000")
 
            lll = Gauss.ManagCons(0) + lll
            mmm = Gauss.ManagCons(1) + mmm
            nnn = Gauss.ManagCons(2) + nnn
 
 
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "l=" & lll
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "m=" & mmm
            TextBox14.Text += Environment.NewLine
            TextBox14.Text += "n=" & nnn
        Next ite
        ' Next nr
 

Good of you to add your code, spranto...

Not a mathematician, but in this case could explain a bit what newton raphson is and what it is supposed to do. Also, could you comment in English. This should help tackle the problem, especially if members here know what newton raphson is.

Sorry for your troubles!

[kadghar]

Hi,
I'm new here, but i've seen they dont like people to help others doing their homeworks. Anyway, i think you to use MatLab to make this with a matrix using Gauss Jordan.

Im not very familiarized with the gauss jordan functions in VB, but if your problem it's about a 3rd grade eq with NR, it could be easier to ask the user the function and the first d.

f(x) = Ax3 + Bx2 + Cx + D
f'(x) = Ex2 + Fx + G

and make the letters (A to G) the inputs for your function.

I saw you used a FOR to make 20 iterations, but i'd use a WHILE instead and some precision limit:

Public Function NR( A B... as Double) as Double

Dim Dou1 as Double '<----this is your precision
Dim Dou2 as Double '<--- this will be the value you obtain
Dim Dou3 as Double '<----this will be the former value you had

Dou1 = .000001
Dou2 = 0
Dou3 = .05

While Abs(Dou3 - Dou2) > Dou1
Dou3 = Dou2
Dou2 = Dou3 - (A*Dou3^3 + B*Dou3^2 + C*Dou3 + D) / ( E*Dou3^2 + F*Dou3^ + G)
Wend

NR = Dou2

End Function

Good Luck

[Dököll]

Hi,
I'm new here, but i've seen they dont like people to help others doing their homeworks. Anyway, i think you to use MatLab to make this with a matrix using Gauss Jordan.

Im not very familiarized with the gauss jordan functions in VB, but if your problem it's about a 3rd grade eq with NR, it could be easier to ask the user the function and the first d.

f(x) = Ax3 + Bx2 + Cx + D
f'(x) = Ex2 + Fx + G

and make the letters (A to G) the inputs for your function.

I saw you used a FOR to make 20 iterations, but i'd use a WHILE instead and some precision limit:

 
Public Function NR( A  B...  as Double) as Double
 
Dim Dou1 as Double  '<----this is your precision
Dim Dou2 as Double  '<--- this will be the value you obtain
Dim Dou3 as Double  '<----this will be the former value you had
 
Dou1 = .000001
Dou2 = 0
Dou3 = .05
 
While Abs(Dou3 - Dou2) > Dou1
Dou3 = Dou2
Dou2 = Dou3 - (A*Dou3^3 + B*Dou3^2 + C*Dou3 + D) / ( E*Dou3^2 + F*Dou3^ + G)
Wend
 
NR = Dou2
 
End Function
 
 

Good Luck

Hello, kadghar!

Nice of you to post you knowledge in this, again, I am blind here...hopefull y it is helpful to spranto:-)