How to define a function as a parameter in another function in VB.NET?

Question

I want to creat a VB Code for brent method (a numerical method) which can takes an analytic function and find the root. How can I do this in VB 2010? the function Brent method takes is like:

Function W_Bazin_Rect_h(ByVal Q As Double,
            ByVal w As Double,
            ByVal a As Double,
            ByVal S As Double) As Double
Dim tempstr As String
If w < 0 Or a <= 0 Then
    tempstr = "Error on input"
    ShowMessageBox(tempstr)
    Exit Function
End If

If Q <= 0 Then
    Return 0
End If
g = 9.81
u = (0.405 + 0.003 / h) * (1 + 0.55 * (h / (h + a)) ^ 2)
Q = ((2 * g) ^ 0.5 * u * w * h ^ (3 / 2)) * (1 - (S / h) ^ 1.5) ^ 0.385

End Function

Should i define brent methode as a class or a function?

I want to initialize the function (i.e Q=1,a=1,w=1,S=1) and then pass the function to the Brent method which could return the value of h. What is the best way to do this in VB.NET? I want to make a general Brent method where I can pass any single valued function and find roots.

I have just started using VB, and from what I have found so far it seems like the tools you have is - to us a delegate for the function - to use a lambda expression for the function - send a pointer/adressOf - to create a function class/structure and submit this to the function

As for now I am most inclined to create a function-class. But I am not really sure how. F.ex. I make different classes for each "uniqe function" I want to integrate, but how can I pass them to the integration function when I need to specify the argument type in the integration-function-call?

This seems like a basic problem which applies to many Math operations, so I think it would be very useful to clarify this.

Answer 1

I wouldn't show the error message in the function. I would return something like Double.NaN, that way you seperate the UI from the logic.

By looking at what you have, you could create something like the Math class. Having your function as shared in a class that could be called MathFunction or something.

Also, you forgot to return a value.