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Re: fit through zero [message #52771 is a reply to message #52714]

Thu, 01 March 2007 01:03

Bringfried Stecklum is currently offline

Bringfried Stecklum
Messages: 75
Registered: January 1996

Member

Reimar Bauer wrote:
> Hi all
>
> I like to use a fit function which I can tell please go to 0,0
>
> How can I do that with e.g. poly_fit or did you know an equivalent routine?
>
> cheers
> Reimar
>
>
Hello Reimar,

since you asked about poly_fit I assume that you want to fit a
polynomial. It would be easy if poly_fit offers a keyword to flag
certain degrees of the polynomial which then would be omitted from the
fit. Since this is not the case I suggest to use svdfit with a user
defined function. A polynomial without the constant term, i.e.
y=ax+bx^2+cx^3... might be O.K.

Note that svdfit uses a polynomial as well if no user-defined function
is specified. However, the polynomial degrees cannot be flagged either.
Since sdvfit is just a wrapper for the hardcoded nr__svdfit this feature
can only be added by the ITT folks.

with kind regards,

Bringfried

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Dr. Bringfried Stecklum
Thueringer Landessternwarte Tautenburg
Sternwarte 5
D-07778 Tautenburg, Germany
Phone: +49-36427-863-54
FAX: +49-36427-863-29
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[Message index]

		fit through zero By: R.Bauer on Mon, 26 February 2007 06:32
		Re: fit through zero By: Paolo Grigis on Thu, 01 March 2007 01:38
		Re: fit through zero By: Bringfried Stecklum on Thu, 01 March 2007 01:03

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