fitting a polynomial to data

M

Mike Kamermans

Hi,

I have three (equal sized) sets of data, T, x and y, and I am trying find
the f(T)=x and f(T)=y polynomial approximations, but I can't seem to find
the option in Excel that will let me do this. I've been assured by some
people that Excel has this option hidden away in it somewhere, but if it's
somewhere then the help function is not finding it when seaching on
"polynomial fit" or even just "polynomial"...

Does anyone know how to do this?

Kind regards,

- Mike Kamermans
 
M

MartinW

Hi Mike,
I use polynomials to achieve a curve fit on an x,y scatter chart with two
sets of data but I don't know how you would go about it for three sets of
data. If you search help for "trendlines" you will at least get an
explanation of excels' polynomial functionality.

HTH
Martin
 
M

Mike Middleton

Mike -

Here are three different ways:

(1) Construct XY (Scatter) charts and use Add Trendline to fit a polynomial.

(2) Use the array-entered LINEST worksheet function.

(3) Arrange T and T^2 in adjacent columns, and use Tools | Data Analysis |
Regression to obtain charts and labeled diagnostics.

- Mike
www.mikemiddleton.com
 

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