The Origin Forum
File Exchange
Try Origin for Free
The Origin Forum
Home | Profile | Register | Active Topics | Members | Search | FAQ | Send File to Tech support
Username:
 Password:
Save Password
Forgot your Password? | Admin Options

 All Forums
 Origin Forum
 Origin Forum
 Advanced Fitting Tool, userdefined function		  New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic

Tobias Henkel

Germany
Posts
Posted - 05/13/2007 :  10:16:53 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Version: origin pro 7.5g (student version)
Operating System: windows xp

Hello,

I encounter some problems using the advanced fitting tool. My user defined function has two independent variables and two parameters.

r=k1*pE*pH/(1+KE*PE)

I want to fit this function to a given data set. I also know the solution for the parameters k1 and KE, however I'm not able to recalculate these parameters using origin.
What happens is essentially the parameter values go to infinity (error values even faster).
Have you any suggestions what the reason might be?

With kind regards
Tobias H.

larry_lan

China
Posts
Posted - 05/13/2007 :  11:47:37 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
I doubt that is because your parameters are highly dependency. During the fitting, could you please look into the following value:



If the value close to 1, it means that the parameters are highly dependence with each other. In this case, since you know the solution for the parameters, you can try to fix one value. Or you can also set bounds for the parameters (Options : Constraints).

If it doesn't work, maybe you can send your data to tech@originlab.com and we can have a try.

Larry
OriginLab Technical Services
Go to Top of Page
  Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
The Origin Forum © 2020 Originlab Corporation Go To Top Of Page
Snitz Forums 2000