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 [SOLVED] Fitting custom-function does not converge		  New Topic  Reply to Topic
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ue0405

Germany
1 Posts
Posted - 11/17/2015 :  11:17:03 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Dear All,

I am sorry to bother you with a (hopefully?) quickly answered to problem:
I have xdata = x and ydata = y and try to fit the following equation, which I entered as custom-made and explicit:

independent variable: x
dependent variable: y
parameters: k_a,m_0,k_d
function form: Oritin C
function: y = k_a*m_0*2.686/(k_a*2.686+k_d)*(1-exp(-(k_a*2.868+k_d)*x))

The function does initiate when I compile it.

I plug in startvalues for all three parameters although I am not 100% that they are correct, but should be in the same order of magnitude.

After a short time after trying to fit I receive the error that the

"fit does not converge - reason unknown. Fitting was done with weights. Check weighting method and error bar values for inconsistency or repeat fitting without weighting."

I translated this error from German, possibly there are some minor deviations to the original message but the meaning should be clear.

I did check the datasets and tryed others as well. It seems to be something integrally wrong with my programming.

Any suggestions what I could try? Please dont hesitate if there is information missing.

Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 2015G (64-bit) Sr2 / b9.2.272 (Home Use)
Operating System: Windows 7 Pro SP1

Best wishes
Ulrich
Edited by - ue0405 on 11/18/2015 09:38:06 AM

SeanMao

China
288 Posts
Posted - 11/17/2015 :  9:43:26 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Ulrich,

From your description, I have successfully compiled the fitting function. However, in order for us to reproduce your problem we will need your sample data to try.

Would you please send the sample data for this fitting function to tech@originlab.com for us to try?

Thanks!

Regards!

Sean

OriginLab Tech. Service
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