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Re: FIT across images [message #66054 is a reply to message #66008]

Sun, 12 April 2009 16:38

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

On Apr 8, 8:23 am, bas.base...@virgilio.it wrote:
> Hi all,
> just to let you know, I now figured it out.
>
> I messed it up with
>
> a. wrong dimensions of “F”, which has to be the same as “fit”
> b. bad use of the * “simple” matrix product.
>
> To simplify matrix products I reformed the S matrix as [n,size,size]
> to [n,m], where m=size*size, and so A to [3,m]. I then used the
> function
>
> iv=replicate(1,(size(x,/dimensions))[0])
> bx = EXP(-x#A[1,*])
> F = (iv#A[0,*]) * bx + iv#A[2,*]
>
> where x is now [n] and F is [n,m]. The procedure
>
> fit=mpcurvefit(x,dummyS,W,A,sigma,function_name='expmap',chi sq=chisq,/
> noderivative,/quiet)
>
> now works, with fit=[n,m], and produces the same results as the double
> forloop procedure does. The funny thing is: it is one hundred times
> slower. Maybe there is a lesson to learn here.

Yep, I would have done the fit with a FOR loop. :-)

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[Message index]

		FIT across images By: bas.basetta on Fri, 27 March 2009 08:28
		Re: FIT across images By: bas.basetta on Wed, 08 April 2009 05:23
		Re: FIT across images By: Craig Markwardt on Sun, 12 April 2009 16:38

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