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 how to writa a programe for user define function
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aird

India
2 Posts

Posted - 03/29/2012 :  05:59:14 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin):
Operating System:

Hi,
I am working on magnetic materials & I want to fit Curie-Weiss Function (Y=C/(T-To)) [in which Y- represent magnetic susceptibility, C- material specific curie constant, T- absolute temperature (in kelvin), To- curie temperature (in kelvin)] in to my data. I have try a lot to generate a user define function for this but not gating success.
If anyone knows about how to create this user-defined function in originpro 8, please help me out in this. I am having a really tough-time regarding this.
Thank you.

Hideo Fujii

USA
997 Posts

Posted - 03/29/2012 :  11:35:34 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi aird,

I think you don't need to define a user-defined function for: 
   y=c/(t-t0)
because Origin has a built-in function Rational4 in Rational category:
   y=c+b/(x+a)
In the fitting process of NLFit, you can fix the value of c (of Rational4) to 0 
(by turning ON the "Fixed" check box in the Parameter tab, and double-click 
the value, and enter 0). 

By the way, for defining a user-defined function, maybe the following 
tutorials may be helpul:

(Video)
http://www.originlab.com/index.aspx?go=Products/Origin/DataAnalysis/CurveFitting/FittingFunctions&pid=1172

(Text)
http://wiki.originlab.com/~originla/howto/index.php?title=Tutorial:User_Defined_Fitting_Function_using_OC

As your Origin version is 8.0, it doesn't have more convenient 
"Fitting Function Builder" (available in 8.5, or later), and 
you need to skip the section in the (Text) tutorial.

Hope this helps.

--Hideo Fujii
OriginLab

Edited by - Hideo Fujii on 03/29/2012 12:34:48 PM
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