Interpolating a list (range) of data?
 

Hi, I've got a project and I am in desperate need of some help:

I'm trying to build a basic program for an offshore oil drilling
application. Given two lists of data (one list being the true vertical depths
(TVD) of an oil well, the second being the measured depth (MD) of the well) I
need to be able to interpolate between the two. Ideally, I would like the
user to be asked for an input, i.e. either the TVD or the MD, and the program
would generate the corresponding value from the other measurement system
(input TVD = output MD, and vice-versa). Calling the actual lists of data
should not be an issue as the datasheets can be copied and pasted into the
workbook. With this in mind, does anyone know of a program that can do so?

Any help/guidance is appreciated. I'm thinking some sort of
central-difference formula is a good interpolation method.