Polynomial Eq Parameters

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Jay - 21 Nov 2006 15:41 GMT

I have an x and y data set for which I want to identify the parameters
(a,b,c) in the following second order polynomial equation. What Excel
functions can do this? I can chart the data and use the trendline function,
but I want to automatically calculate the parameters in individual cells that
I can reference in another formula. Thanks, J

y = ax^2 + bx + c

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Jay

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Jay - 21 Nov 2006 16:08 GMT

I would also like to be able to calculate the R-squared value for polynomial
equation as well. Same as the chart trendline feature produces, but with the
outcome in a cell rather than displayed on a chart.

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Jay

> I have an x and y data set for which I want to identify the parameters
> (a,b,c) in the following second order polynomial equation. What Excel
[quoted text clipped - 3 lines]
>
> y = ax^2 + bx + c

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Bernard Liengme - 21 Nov 2006 17:25 GMT

Use LINEST as demonstrated at
http://people.stfx.ca/bliengme/ExcelTips/Polynomial.htm
best wishes

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Bernard V Liengme
www.stfx.ca/people/bliengme
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>I have an x and y data set for which I want to identify the parameters
> (a,b,c) in the following second order polynomial equation. What Excel
[quoted text clipped - 5 lines]
>
> y = ax^2 + bx + c

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Jay - 21 Nov 2006 18:57 GMT

I would also like to be able to calculate the R-squared value for the
polynomial
equation. The chart trendline feature gives an R-squared, but displayed on
a chart rather than in a cell .

Signature

Jay

> Use LINEST as demonstrated at
> http://people.stfx.ca/bliengme/ExcelTips/Polynomial.htm
[quoted text clipped - 8 lines]
> >
> > y = ax^2 + bx + c

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Mike Middleton - 21 Nov 2006 19:10 GMT

Jay -

Use LINEST as suggested by Bernard. The value of R-squared is one of the
outputs of the LINEST function. See Excel's Help for details.

- Mike
http://www.mikemiddleton.com

>I would also like to be able to calculate the R-squared value for the
> polynomial
[quoted text clipped - 15 lines]
>> >
>> > y = ax^2 + bx + c

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