how to find root in Excel/VBA?

[cfman]

Let's say I want to use Newton's root finding method:

I've already programmed my function in VBA,

now I want to use Newton's method to find the root of that function in
VBA...

I am guessing that in Excel it has built-in function to do this,

But what is that root-finding Newton's function and how to use that Excel
built-in function in VBA?

Thanks a lot

 

[cfman]

Maybe we have a simpler way to do the Newton's rootfinding:

Let me describe my current situation more clearly:

Currently in my Excel worksheet,

Depending on a parameter "y" in Cell(12, 2),

When we click a button "GO", in Cell (13, 2) I will get a number(from a
function call to VBA macro, which I wrote previously), Cell(13,2) is the
function value which changes along with the "y" value in Cell(12, 2).

Now I want to use the Newton's method in Excel,

to find the parameter "y" to get the Cell(13,2)'s function value to be equal
to 100.

I want the correct "y" value to be found by Newton's method and displayed
back in Cell(12, 2) and I want the iterative procedure(i.e. the function
values at each root finding procedure) to be displayed and highlighted
somewhere in the Worksheet also.

I guess I can do this simply in Excel based on my function already written
in VBA...

How to do that? Thanks a lot

 

[NickHK]

Have you looked at the Tools>Solver ?
Requires the Solver addIn installed.

NickHK

 

[Mike Middleton]

cfman -

Have you tried Tools | Goal Seek ?

- Mike
http://www.mikemiddleton.com