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 Nolinear curve fit		  New Topic  Reply to Topic
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hmzahb

Morocco
2 Posts
Posted - 03/06/2024 :  7:37:28 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 2024
Operating System: Windows 11

Hi, I am trying to do a fitting for the data bellow but it gives me the error message, so I am not sure is the fitting acceptable or in general how can I find the best fitting for this curve ?






1423.59 21.95
1430.57 11.18
1449.69 7.69
1481.98 3

Shirley_GZ

China
Posts
Posted - 03/07/2024 :  02:07:58 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi hmzahb,

Please use the function "ExpDec1" instead, in which the parameter x0 and A1 are not independent.
https://www.originlab.com/doc/Origin-Help/ExpDec1-FitFunc

Thanks,
Shirley



Originlab Technical Service Team
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hmzahb

Morocco
2 Posts
Posted - 03/07/2024 :  05:32:56 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thank you, I did but it seems didn't works well
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easwar

USA
1964 Posts
Posted - 03/12/2024 :  10:07:57 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi hmzahb,

The function you chose initially (ExpDecay1) is the right one, as your data has an offset in X.
But note that this function has 4 parameters and you only have 4 data points, thus you have no degrees of freedom to perform the fit.

Try fixing the x offset parameter to the x value of the first data point, and you will get better results.



Easwar
OriginLab
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