From: Axel Etzold <AEtzold@...>
Date: 2008-11-17T09:04:19+09:00
Subject: Re: Power Trend Line


Dear Chris,


>> Im using some graphing software to produce charts which contain various
>> lines.  One line i need to produce is a power trend line from an array
>> dataset.

> 
> I interpreted the original message to mean code to fit a, for example, 
> polynomial of a given order to some data. It's been a while since I 
> played with it but can Gruff do this ?

No, I don't think so, it's just for graphing (and for lines, rather than polynomials)
rather than fitting, for which the software you proposed can be used.
Maybe you're right that the OP wanted some fitting algorithm.

A good place to look for is "Linear Regression" (can be used also to determine
coefficients of polynomials). There is an example for Rb-gsl here:

http://rb-gsl.rubyforge.org/fit.html#2 , chapter 5 .

Once you've calculated it, you can choose a nice graphing output software ...

Best regards,

Axel 


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