Let's say I have 2 values: one at F1 and the other at F8.
By using linear interpolation I can solve for F2, F3, F4, F5, F6 and F7
(the two other values that are needed for the interpolation are not
relevant for my problem).

Problem:
The two values that I have are not always in F1 and F8.
They now can be at F2 and F7.

Question:
How can I apply the interpolation without knowing where exactly my two
values appear? I do know for sure that I have two values and that there
are cells in between those two values that are needed to take
interpolated values...

I hope I am clear.

Thanks.