| T O P I C R E V I E W |
| Tobias Henkel |
Posted - 05/13/2007 : 10:16:53 AM
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. |
| 1 L A T E S T R E P L I E S (Newest First) |
| larry_lan |
Posted - 05/13/2007 : 11:47:37 AM
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 |
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