I have custom function wrrtien by me
Say in this
l1,l2 are values of A that are available in the matrix
d1, d2 are the nearest values B available in the matrix
dx is interpolation required in ranne B

Function Intepolete(l1, l2, d1, dx, d2)
If l2 l1 And d1 d2 Then
Intepolete = l1 + (l2 - l1) / (d1 - d2) * (d1 - dx)
End If
If l2 < l1 And d1 d2 Then
Intepolete = l1 - (l1 - l2) / (d1 - d2) * (d1 - dx)
End If
If l2 < l1 And d1 < d2 Then
Intepolete = l2 + (l1 - l2) / (d2 - d1) * (d2 - dx)
End If
If l2 l1 And d1 < d2 Then
Intepolete = l2 - (l2 - l1) / (d2 - d1) * (d2 - dx)
End If
If l2 = l1 Or d1 = d2 Then
Intepolete = l1
End If
End Function

In this i have interpolation in one side say A, you need from both sides
So enhance the code for that.
I use this function as custom function on worksheet, using absolute and
mixed refrences I can mange to interpolete in variety of ranges, but it has
only one direction of interpilation.



"nelg" wrote in message
...

Tom,

The A*B is just a simple representation. The actual sheet has no
trending values between A and B. It is the process I am looking for.

Thanks for you comments so far though!

Glen.


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