1. ## Interpolation

Hi all

I have 4 points with 4 associated values:

2=0.32
5=0.52
10=0.43
30=0.97

What I need to do is expand this list to have a total of 10 points - please could somone point me in the right direction to do this?

Thanks for any information.

2. Are you saying that you have four points, the first being (x, y) = (2, 0.32), and that you are needing to do some sort of regression...?

3. Yes thats what I am after

Thanks,

4. What sort of regression are you supposed to find? For instance, an exact cubic polynomial can be put through the four points, but you may have been instructed, or otherwise have knowledge specifying, to use an exponential formula, etc.

Thank you!

5. If i were to use linear interpolation to create a point between 2 and 5, say 3...

3=((5-3)/3)*0.32+((3-2)/3)*0.52=0.3867

and 8 between 5 and 10...

8=((10-8)*0.52)/5+((8-5)*0.43)/5=0.466

this is the linear interpolation used in statistics on the tables.

((upperx-x)*f(lowerx))/(upperx-lowerx)+((x-lowerx)*f(upperx))/(upperx-lowerx)

If thats what is meant by interpolation