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 global fit of multiple data sets and functions		  New Topic  Reply to Topic
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gdroogmans

Belgium
6 Posts
Posted - 03/18/2004 :  05:06:19 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
I am trying without success to fit several data sets with two different functions, i.e. some data with the first function, others with the second function.
Does anyone know a solution for this problem?

Mike Buess

USA
3037 Posts
Posted - 03/18/2004 :  08:36:44 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
This is how I would go about it using the NLSF fitter...

1. Function->Edit or New: combine the functions as follows

y = A * func1(x) + (1-A) * func2(x)

2. Action->Dataset: check Fit Multiple datasets at the bottom and Add each dataset to the fitting session.

3. Action->Fit: fix A to 0 or 1 for each dataset and otherwise make sure all parameters are sensibly initialized. Then click one of the iterate buttons.

...Besides fixing A to 0 or 1 you may also need to fix the parameters for the function that is not used to some reasonable values.

Mike Buess
Origin WebRing Member

Edited by - Mike Buess on 03/18/2004 08:56:47 AM
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gdroogmans

Belgium
6 Posts
Posted - 03/18/2004 :  11:35:17 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thanks for your fast and ingenious reply
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