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 Nonlinear curve fitting with multiple variable

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T O P I C    R E V I E W
Showmik Posted - 07/02/2019 : 01:23:31 AM
OriginPro 8 SR4, v8.0951(B951)
Operating System: Windows 7

Hello,

I want to generate a correlation between multiple variables using the nonlinear curve fitting. I want to use the formula y=C*x1^a*x2^b. Here, x1 and x2 are the independent variables and y is the dependent variable. How can I create such a user-defined function and use the relevant experimental data for generating the equation? In this case, the parameters would be a, b and C. I have experimental data for y, x1, and x2.
Any kind of help would be highly appreciated. thanks

Showmik
4   L A T E S T    R E P L I E S    (Newest First)
Showmik Posted - 07/03/2019 : 10:30:59 AM
Thanks for the help. I was able to perform the nonlinear fitting by my own user-defined function.

Showmik
Chris D Posted - 07/02/2019 : 09:33:27 AM
you can actually create your own fitting function that accepts multiple independent variables.

Here is a tutorial:
https://www.originlab.com/doc/Tutorials/Fitting-MultiIndepVar

And here are the docs about creating a user defined fitting function:
https://www.originlab.com/doc/Tutorials/UserDef-FitFunc

Creating a user-defined fitting function isn't "click-click" easy-peasy, but they are not particularly hard to do either if you follow the steps.

I hope this helps!

Thanks,
Chris Drozdowski
Originlab Technical Support
Showmik Posted - 07/02/2019 : 04:03:54 AM
Thanks for the tutorial. I checked it but my problem is while fitting with multiple variables. The tutorial shows only 1 dependent and 1 independent variable and how to use it. In my case, I need to find the correlation with 1 dependent and 2 independent variables. Hope you understand the situation

Showmik
AmandaLu Posted - 07/02/2019 : 03:34:21 AM
Hi,

Please refer to this tutorial:

https://www.originlab.com/doc/Tutorials/UserDef-FitFunc

Thanks,
Amanda
OriginLab Technical Service


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