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linamaho

1 Posts
Posted - 03/09/2009 :  2:34:59 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hello

I've been trying to make a custom fit by using the following equation y = A+ B*cos(2x), but after defining the new function in the fitting function organizer nothing appears when I say that makes the fit. On the other hand, could you tell me how I define the initial values of my parameters?

Thank you.

Deanna

China
Posts
Posted - 03/09/2009 :  11:16:41 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

Please read the following section and the help file of the Fitting Function Organizer:
http://www.originlab.com/www/helponline/Origin8/en/regression_and_curve_fitting/user-defined_fitting_functions.htm#InitParams





Deanna
OriginLab Technical Services
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Femtosecond15

7 Posts
Posted - 06/19/2009 :  2:19:23 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hello,

I would like to fit a function with a user-defined equation. The formula I want to use is called hyperbolic secant. Here is the formula:

y = A*(2/exp(x-x0)+exp(-x+x0))^2

I did everything exactely as described in the fitting tutorial but when I try to fit my data nothing happens. I can fit e.g. a Gaussian on the data. So the data itself are ok.

Does anyone know where the problem might be?

Thanks a lot.
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Echo_Chu

China
Posts
Posted - 06/22/2009 :  01:35:08 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

Please look at following tutorial of how to fit with user-defined functon.
http://wiki.originlab.com/~originla/howto/index.php?title=Tutorial:User_Defined_Fitting_Function_using_OC

Have you got any error message when you fit your data? Best you can provide us your fdf file and sample data so that we can look into it.

You can send it by guidelines in this page
http://www.originlab.com/index.aspx?s=1&lm=123&pid=752


Echo
OriginLab Corp
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