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Läouu

Germany
2 Posts
Posted - 12/24/2009 :  11:50:09 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin): 8
Operating System:

Hey,

i have plotted some data consisting of x-values, y-values and y-errors. Now i want to do a curve fit basically like in this tutorial
http://www.youtube.com/watch?v=di-ZiiVMPlw
(data selection from the graph)
My problem is now that when i open the fitting dialog it says "Error during compilation for parameters init" and the InputData window is empty. The only data i can choose for input is the data-table. But i need to be able to select the data range from the graph. Anyone got an idea?
Oh yeah, while i'm at it. Is there any possibility to display the fit parameters and the reduced (chi)^2 in the same window as the fit?

Best Regards,
Jan

Shirley_GZ

China
Posts
Posted - 12/25/2009 :  12:38:18 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Jan,

I suppose you defined the function by yourselves in Origin 8. The error message “Error during compilation for parameters init†means there are some wrongs with the initial code. Please check the function file (.FDF).

If you active the graph window, you can select data from graph. Otherwise, only source data in worksheet can be selected as Input data.

When you do fitting in the NLFit dialog, you can see all fit parameters in the Parameter tab, http://www.originlab.com/www/helponline/Origin8/en/regression_and_curve_fitting/parameters_tab_upper_panel.htm

The reduced chi-sqr will be displayed in the Message tab after you click the Calculate Chi-Square, 1 Iteration or Fit until Converge button, http://www.originlab.com/www/helponline/Origin8/en/regression_and_curve_fitting/message_tab_lower_panel.htm

Thanks,
Shirley

Originlab Technical Service Team
Edited by - Shirley_GZ on 12/25/2009 12:39:22 AM
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Läouu

Germany
2 Posts
Posted - 12/25/2009 :  10:37:16 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Shirley,

thank you for you reply . I think i got the fitting to work now (By the way i used the Gauss-function). I don't know exactly why but if i highlight all columns and use button for the scatter-plot in the lower right corner, i get the correct graph and i'm able to fit and select the data range from the graph.
When i do the fit there appears a table in the plot including the function used for the fit, the fit parameters and the Adj. R-Square. My question regarding the Chi-Square was if it was possible to include the reduced Chi-Square into this table. I think i didn't make myself clear last time .

Best Regards,
Jan
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Laurie

USA
404 Posts
Posted - 12/29/2009 :  10:52:11 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Jan,

By default, this table should contain the Reduced Chi-Sqr value as well. You can customize this table and this link will discuss this further:
http://www.originlab.com/www/helponline/Origin8/en/regression_and_curve_fitting/custom_table_theme_template.htm

Please make sure you have SR6, the latest service release for Origin 8.

Laurie

OriginLab Technical Support
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