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 Fit which has multiple solutions		  New Topic  Reply to Topic
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pb

Italy
8 Posts
Posted - 08/25/2004 :  06:29:50 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
I have to perform a fit with a quite complex fitting function, of about 10 free parameters.I wrote this function in the NLSF module, and it works. However, I'm aware of the existance of various solutions (with similar chi square) depending on the initialisation of the fitting parameters. It takes long to initialise randomly the parameters and see which solution comes out.

I was wondering if it is possible to write a script which allows to explore with more completeness the multidimensional space of the fitting parameters, automatically changing the initialisation within a predefined range (Origin 7.5).

many thanks

paola

Mike Buess

USA
3037 Posts
Posted - 08/25/2004 :  1:29:56 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi paola,

The NLSF tool is fully scriptable. Search for the NLSF object in your LabTalk Language Reference for a list of NLSF properties and methods. You'll also find a few examples at the bottom of that topic that might help get you started.

...There are also some free add-on modules at OriginLab's File Exchange that might give you some ideas for programmed NLSF fitting in Origin C.

http://www.originlab.com/FileExchange/index.aspx?C=5&cid=2

Mike Buess
Origin WebRing Member

Edited by - Mike Buess on 08/25/2004 1:40:28 PM
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carsten

Switzerland
78 Posts
Posted - 08/25/2004 :  3:26:55 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
I would like to make a comment on that issue. There exist a strategy to tackle such problems by using a so called "Genetic algorithm".
Maybe this could be a fit algorithm for future Origin releases?
(Matlab users can use this sort of fit tool already. Also there are existing further programs,see internet)

Carsten
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