newton raphson 1 variable X^3-X+2

Option Base 1
Dim spr As New Spreadsheet
Sub Main
Dim akar0, akar1, beda As Double
Dim Nilai1, nilai2 As Double
Dim baris As Integer
akar0=-1
spr.Visible = True
spr.Header ="Latihan ke 7 Newton Raphson"
nilai0=NilaiFungsi(akar0)
baris =1
Do

spr.Cells(baris,1) = baris 'baris
spr.Cells(baris,2) = akar0 'akar0
spr.Cells(baris,3) = NilaiFungsi(akar0) 'nilai fungsi
spr.Cells(baris,4) = NilaiFungsiTurunan(akar0) 'nilai turunan

akar1 =akar0 -(spr.Cells(baris,3)/spr.Cells(baris,4))

spr.Cells(baris,5) = akar1 'akar1
spr.Cells(baris,6) = NilaiFungsi(akar1) 'Nilai fungsi akar1
spr.Cells(baris,7) = NilaiFungsiTurunan(akar1) 'Nilai fungsi Turunan akar1

baris=baris+1
beda =akar1-akar0
akar0=akar1
If baris >=10 Then spr.AddCases (baris,1)
Loop Until (Abs(beda) <=1.0E-6)

End Sub
Function NilaiFungsi(xi As Double) As Double
NilaiFungsi = xi^3 - xi + 2
End Function

Function NilaiFungsiTurunan(xi As Double) As Double
NilaiFungsiTurunan = 3*xi^2 - 1
End Function