On Mon, 28 Jan 2008 11:41:00 -0800, serching table <serching
wrote:

I need to interpolate the following data points :
1.3330 and 1.4270 at intervals of 0.5
could you provide a simple formula ? thank you

It's not possible.

1.3330 + 0.5 = 1.8330 (already grater than 1.4270)

Perhaps you mean something different?
--ron