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Help with least squares on non-linear function [message #85657]

Sat, 24 August 2013 12:14

stefan.meingast
Messages: 30
Registered: June 2012

Member

Hey

I finally want to enjoy at least some time of the weekend, but I am stuck at one problem tonight for which I still would like to find a solution.

I have a bunch of measurements in an array y which depending basically on another variable x. I want to do a least-squares fit to a non-linear function, which would be very easy if I just wanted e.g. a polynomial fit. My problem is now that there is another parameter coming into play (here: k), so the function I want to fit in the end looks like this (though the order should be variable in the end which in this example is set to 3):

https://dl.dropboxusercontent.com/u/16787607/formula.jpg

where the a_i are the coefficients I want to determine.

I have been trying to figure out what the best way might be to do such a fit, but this turns out to be much more complicated than I thought...

I hope some of you may have a hint

many thanks!!!
:)

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[Message index]

		Help with least squares on non-linear function By: stefan.meingast on Sat, 24 August 2013 12:14
		Re: Help with least squares on non-linear function By: stefan.meingast on Sat, 24 August 2013 12:20
		Re: Help with least squares on non-linear function By: Phillip Bitzer on Sat, 24 August 2013 14:10
		Re: Help with least squares on non-linear function By: stefan.meingast on Sat, 24 August 2013 14:32
		Re: Help with least squares on non-linear function By: Phillip Bitzer on Sat, 24 August 2013 14:53
		Re: Help with least squares on non-linear function By: Heinz Stege on Sun, 25 August 2013 05:40

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