Fwd: [ferret_users] fourth-order polynomial least square

To: ferret <ferret_users@xxxxxxxx>

Subject: Fwd: [ferret_users] fourth-order polynomial least square

From: Peter Szabo <szabpet83@xxxxxxxxx>

Date: Thu, 17 Mar 2011 11:29:03 +0100

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Thank You, Peter

---------- Forwarded message ----------
From: Peter Szabo <szabpet83@xxxxxxxxx>
Date: Wed, Mar 9, 2011 at 2:36 PM
Subject: Re: [ferret_users] fourth-order polynomial least square
To: Brockmann Patrick <Patrick.Brockmann@xxxxxx>

Thanks Patrick,

It seems promising, but I have no clue at all how I could make this EF work.

I mean I have not done a adding a single EF to my ferret.

Would you help me in that? I checked it on the ferret website, but it seems too hard for me- or i can blame it on the lack of time. :)

Thanks, Peter

On Tue, Mar 8, 2011 at 2:26 PM, Brockmann Patrick <Patrick.Brockmann@xxxxxx> wrote:

I would like to fit a fourth-order polynomial least-square fit (a curve) to a time-series. Is there a chance to achieve this with Ferret? I know regresst.jnl, but it only does a linear regression. Your effort or any help would be appreciated.

Hi Peter,
Relative to this polynomial fit, you may find useful some interpolation technics
from http://paulbourke.net/miscellaneous/interpolation/

I compute some of them as external functions (applied on zaxis).
Studies on parameters (biais, tension) from the Hermine interpolation implentation gives:
http://dods.ipsl.jussieu.fr/brocksce/ferret_ef/zinterpolate/spline_hermite_bias.swf
http://dods.ipsl.jussieu.fr/brocksce/ferret_ef/zinterpolate/spline_hermite_tension.swf

External function can be found from:
http://dods.ipsl.jussieu.fr/brocksce/ferret_ef/zinterpolate

Patrick

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LSCE/IPSL, Laboratoire CEA-CNRS-UVSQ
Data Analysis and Visualization Engineer
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