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DeborahH

Canada
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Posted - 10/20/2004 :  10:58:04 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Version (Select Help-->About Origin): Origin 7
I would like to perform curve-fitting on a function that involves an integral. The data I would like to fit corresponds to the result of the integral. The function including the parameters to be fit corresponds to the function to be integrated? Am I able to perform such an operation with Origin? If so, how? I was unable to find a suitable integration command.

Thanks so much.

easwar

USA
1965 Posts
Posted - 10/20/2004 :  11:08:11 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

There is a knowledge base item on how to do this with script:
http://www.originlab.com/www/support/resultstech.aspx?ID=121&language=English

and you can look at the end of the following post for a discussion on how to do summation in Origin C while fitting:
http://www.originlab.com/forum/topic.asp?TOPIC_ID=2586

Easwar
OriginLab
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DeborahH

Canada
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Posted - 10/21/2004 :  3:56:00 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
I am unfortuantely still having trouble.
More specifically, I have datasets x and y.
The desired fit for y (with parameters P1, P2, P3, P4, P5 and P6) is:
y=(integral_from_0_to_x(P1*exp(-(x^2)/(P2^2))+P3*exp(-(x^2)/(P4^2))
+P5*exp(-(x^2)/(P6^2))))/(P1*(P2^2)+P3*(P4^2)+P5*(P6^2))

Is it impossible to fit this function with "Form" set to "Equations"?
What is the easiest way to fit this function?

Thanks again.
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easwar

USA
1965 Posts
Posted - 10/22/2004 :  09:36:34 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

If you follow the kbase item on computing integral using script, you will need to set the equation form to Y-Script. If you want to use Origin C, you will need to check the "use Origin C" checkbox.

Easwar
OriginLab
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