Interpolating an x, y point from known x's and y's

[Steve]

Hi

This is probably a simple task and it is my own lack of experience in
Excel -- I would like to derive a y value for an arbitrary x value from a
array of known x's and known y's for some unknown function y = f(x) a la:

known x, y
0.123, 4.567
0.257, 10.4567
0.4321, 20.3241
0.703, 10.345
0.804, 2.345

say I want to derive a y value for x=0.5 from this data set using a linear
or higher order fit -- is there an appropriate worksheet function for this
or do I have to resort to programming?

Many thanks in advance.
Steve

[Bernard Liengme]

You can nearly always fit N points to polynomial of N-1 power.
You can make a chart and use Add Trendline
To put the coeffienceints in worksheets cell use LINEST
For more on:Polynomial, non-linear, Trendline Coefficients
and Regression Analysis

http://www.tushar-mehta.com/excel/ti...efficients.htm
http://www.stfx.ca/people/bliengme/E.../Polynomial.ht

--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"Steve" <[email protected]> wrote in message
news:[email protected]...
> Hi
>
> This is probably a simple task and it is my own lack of experience in
> Excel -- I would like to derive a y value for an arbitrary x value from a
> array of known x's and known y's for some unknown function y = f(x) a la:
>
> known x, y
> 0.123, 4.567
> 0.257, 10.4567
> 0.4321, 20.3241
> 0.703, 10.345
> 0.804, 2.345
>
> say I want to derive a y value for x=0.5 from this data set using a linear
> or higher order fit -- is there an appropriate worksheet function for this
> or do I have to resort to programming?
>
> Many thanks in advance.
> Steve
>
>