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pazmush

14 Posts
Posted - 12/19/2008 :  10:21:52 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Can anyone give me a rough guide or tutorial on how to fit my own nonlinear function to some data?

pazmush

14 Posts
Posted - 12/19/2008 :  11:38:09 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
right, sorry, i think i understand the fitting process now, but when i perform an iteration origin seems to freeze up, what do you think might be wrong?
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Shirley_GZ

China
Posts
Posted - 12/22/2008 :  02:34:18 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi pazmush,

I'm not sure where the problem is, Would you please check your steps according to the below pages?

http://www.originlab.com/www/helponline/origin8/en/origin.htm#Regression_and_Curve_Fitting/User-Defined_Fitting_Functions.htm

http://www.originlab.com/www/helponline/origin8/en/origin.htm#Regression_and_Curve_Fitting/The_Fitting_Function_Organizer_dialog_box.htm

If still any problem, please send the FDF file, which can find through the FileName(.FDF) item in the Fitting Function Organizer dialog, and the data to tech@originlab.com, quote this post in the E-mail.

Thank you!

Shirley

Originlab Technical Service Team
Edited by - Shirley_GZ on 12/22/2008 02:34:48 AM
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pazmush

14 Posts
Posted - 12/29/2008 :  11:38:55 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
hi my emails havent been getting through so i thought i'd post here

sorry to bother you again but ive got this far now (see attachments).
As you can see my problem is that my data doesnt start from zero, how can i get around this problem with the curve fitting?




i used the formula;

y = ((h*exp(-a*x))/((3.14*b*(x+1/a))^0.5))*(exp((-(c-d*x)^2)/(b*(x+1/a))))

and parameters

h=5
a=10000
b=0.01
c-0.065 (fixed)
d=90

some of these parameter need a little fiddeling as c should equal 0.0025?
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Deanna

China
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Posted - 12/30/2008 :  02:56:30 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi, you also send us an email. I have replied it. Please check.

Deanna
OriginLab Technical Services
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