Visual Basic Instinct : Using Newtonian Approximation to solve equations

Using Newtonian Approximation to solve equations

If you want to solve polynominal equations, you can use the Newton-Raphson method of approximating the solutions. This routine takes parameters too.

Author: Jim Brown


Function NewtonApprox (root As Double, tolerance As Double, maxIter As Integer, params() As Double) As Integer

  Dim iter As Integer
  Dim h As Double, diff As Double

  iter = 0
  Do
     h = .01 * root
     If Abs(root) < 1 Then h = .01 ' calculate guess refinement 
     diff = 2 * h * MyFx(root, params()) / (MyFx(root + h, params()) - MyFx(root - h, params())) ' update guess root="root" diff 
     iter = iter + 1 
  Loop While (iter <= maxIter) And (Abs(diff) > tolerance)

  If Abs(diff) <= tolerance Then 
     NewtonApprox = True
  Else 
     NewtonApprox = False
  End If 

End Function