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Karmar
United Kingdom
6 Posts |
 Posted - 04/27/2021 : 4:13:35 PM
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Hi,
I would like to create a new function for fitting the data. The function is y = exp(-(x/a)^b) with 0< = b <=1, but I have no idea what to put to Parameter Init.
Any help will be much appreciated.
Origin Ver. OriginPro 2021 (64-bit)
Operating System: WIN10 |
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YimingChen
1613 Posts |
Posted - 04/27/2021 : 4:19:48 PM
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Hi,
Please refer to this tutorial on defining a fitting function.
https://www.originlab.com/doc/Tutorials/UserDef-FitFunc
Step 7 shows settings of Initial Parameter. By default those values are set to 1. You can start with that for the fitting. If the fitting fails to converge, you may change the Initial guess to more random values. Again the initial guess depends on the data. If you still can't get good fit. Please send us your dataset.
James |
Edited by - YimingChen on 04/27/2021 4:21:07 PM |
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Karmar
United Kingdom
6 Posts |
Posted - 04/27/2021 : 4:51:17 PM
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Thank you very much James. It has worked. I got the fit, but there is a huge error for a (80742,37162 ± 17881,27345). Is there anything else I can do to optimize the fit or my data are not good enough?
Data: 0, 1; 1800, 0.7; 3600, 0.61; 7200, 0.53; 14400, 0.5; 28800, 0.43; 57600, 0.39; 86400, 0.4
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YimingChen
1613 Posts |
Posted - 04/28/2021 : 10:33:20 AM
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This is the optimal fitting result on this dataset. You may consider adding more data for less fitted error.
Yiming
quote:
Originally posted by Karmar
Thank you very much James. It has worked. I got the fit, but there is a huge error for a (80742,37162 ± 17881,27345). Is there anything else I can do to optimize the fit or my data are not good enough?
Data: 0, 1; 1800, 0.7; 3600, 0.61; 7200, 0.53; 14400, 0.5; 28800, 0.43; 57600, 0.39; 86400, 0.4
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Nonlinear fitting