The Origin Forum
File Exchange
Try Origin for Free
The Origin Forum
Home | Profile | Register | Active Topics | Members | Search | FAQ | Send File to Tech support
Username:
 Password:
Save Password
Forgot your Password? | Admin Options

 All Forums
 Origin Forum
 Origin Forum
 fitting a nonlinear function		  New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic

noether08

2 Posts
Posted - 07/07/2008 :  7:28:55 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hi,
here´s my problem:
I´ve got four point and want to fit this function:
y=P1*(1-exp(-0.213*P2*x)*J0(i*0.213*P2*x))
with P1 and P2 being the parameters ad J0 being the zeroth bessel function.
But when i try to fit this function, Origin always says:
"Unable to compile user defined function"

Does anybody know, what i´m doing wrong?

larry_lan

China
Posts
Posted - 07/08/2008 :  12:33:39 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Not sure about how you define J0, maybe you should add a * between J0*(

Thanks
Larry
OriginLab Technical Services
Go to Top of Page

Fay_Guo

China
Posts
Posted - 07/08/2008 :  01:49:54 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Could you give us your exact formula?

Does your "bessel function" is the same as http://en.wikipedia.org/wiki/Bessel_function



Thanks
Fay
Originlab Technical Services
Go to Top of Page

noether08

2 Posts
Posted - 07/08/2008 :  12:45:10 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
The formula in my first post was the one that was given.

I think, JO should be the zeroth bessel function of the first kind, like on wikipedia, with (i*0.213*P2*x) being the variable of the Bessel function.

I think the problem is that the variable is complex; when i tried J0(0.213*P2*x), i got a fit function from origin.
Edited by - noether08 on 07/08/2008 12:47:10 PM
Go to Top of Page
  Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
The Origin Forum © 2020 Originlab Corporation Go To Top Of Page
Snitz Forums 2000