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Re: Poly_Fit [message #85439 is a reply to message #85437]

Tue, 06 August 2013 14:42

wlandsman
Messages: 743
Registered: June 2000

Senior Member

The output keywords to POLY_FIT can be useful

IDL> result = POLY_FIT(lamk, speck, 4, STATUS=STATUS, YFIT=yfit)

The value of status will tell you if there were any problems encountered during the fit.

You can use the yfit vector to see if the fit makes sense

IDL> plot,lamk,speck
IDL> oplot, lamk, yfit

As noted in the documentation to the STATUS keyword, fitting problems -- especially if they only occur when fitting high orders -- can often be solved by doing everything in double precision.

--Wayne

On Tuesday, August 6, 2013 3:07:29 PM UTC-4, dta...@gmail.com wrote:
> I'm having a problem using poly_Fit in IDL. It doesn't generate the same coefficients as excel especially for orders > 3? Does anyone know?
>
>
>
> result = POLY_FIT(lamk, speck ,4)
>
>
>
> Thanks,

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[Message index]

		Poly_Fit By: dtakir on Tue, 06 August 2013 12:07
		Re: Poly_Fit By: Heinz Stege on Tue, 06 August 2013 13:45
		Re: Poly_Fit By: wlandsman on Tue, 06 August 2013 14:42

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