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Initialization of parameter in NLFit

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will2008

China
10 Posts

Posted - 08/24/2018 : 12:56:21 AM

Origin Ver. and Service Release (Origin 2018):
Operating System:Window 10

I would like to use release kinetic models to fit my data. For that purpose, I built the several functions as user-defined in nonlinear curve fitting. But I have to provide a Code to be executed to initialize parameters.

Due to my weakness in programming a friend of mine send me the initialization codes (example as shown in attached picture) that he used in excel. I would like to if it is possible to copy that code in origin. The codes are written in Visual Basis.

Secondly please can origin has inbuilt functions for kinetic (dissolution) release such as:

Zero-order model: y=k*t
First order model: y=1-exp(-k*t)
Higuchi model: y=k*t^0.5
Hixson-Crowell model: y=1-(1-k*t)^3
Korsmeyer-Peppas model: y=k*t^n
Peppas-Sahlin model: y=kd*t^m+kr*t^(2*m)
Kopcha model: y=A *t^0.5 + B * t

Thanks

Edited by - will2008 on 08/24/2018 12:57:58 AM

yuki_wu

896 Posts

Posted - 08/24/2018 : 03:53:21 AM

Hi,

1# I am sorry that Origin only allows using LabTalk Script and Origin C to initialize parameters or set initial values in NLFit dialog directly. More info please read:
https://www.originlab.com/doc/Origin-Help/FitPara-INI

2# Please take a look at this tutorial and see if this applies to you:
https://www.originlab.com/doc/Tutorials/Linear-Fit-For-Kinetic-Models

Regards,
Yuki

OriginLab

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