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mongmara

Cambodia
2 Posts
Posted - 07/31/2010 :  01:12:57 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin):
Operating System:

I have tried to fit (x,y) data points using the model y=A*exp(B*x)+C using least square principle. I arrive at solving nonlinear system of equation

using Newton Method and/or Steepest descent method. For Newton Method the solution converges for some initial solution while, Steepest descent method, It doesn't converge. Anyone have any idea? Please help.
mongmara@gmail.com

Mong Mara

larry_lan

China
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Posted - 08/01/2010 :  10:04:30 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi:

The Origin fitter supports explicit function only. You can fit a model like y=A*exp(B*x)+C. However, implicit equations, like the equation you posted, cannot be solved in Origin.

Thanks
Larry
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mongmara

Cambodia
2 Posts
Posted - 08/04/2010 :  7:49:06 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
You said I could fit the model. How Can I fit? Any idea or instruction?

Mong Mara
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Shirley_GZ

China
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Posted - 08/05/2010 :  11:17:59 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

To fit the model like y=A*exp(B*x)+C, please follow this tutorial page,

http://www.originlab.com/www/helponline/Origin/en/mergedProjects/Tutorial/Tutorial/User_Defined_Fitting_Function_using_OC.html

Thnaks,
Shirley

Originlab Technical Service Team
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