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tratto2
USA
1 Posts |
 Posted - 10/04/2001 : 9:52:05 PM
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Anyone know how to include a modified bessel function in a user defined nonlinear curve fit function?
Thanks,
Tim |
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easwar
USA
1965 Posts |
Posted - 10/05/2001 : 5:55:08 PM
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Tim,
You can use any of the Bessel functions documented under the special functions category (in the LabTalk manual or from the product help files) such as J0(x), J1(x), Jn(x), Y0(x) etc.
You can use these function in writing your user-defined fitting equation. For instance, your fitting function may be something like:
y = a*x + b*Jn(x,2);
which would describe a 2nd order Bessel function riding on a straight line of slope a.
With the functions Jn and Yn, you may get better results by fixing the order in the fitting function and not letting this be a fitting parameter.
If you need more help, please send an e-mail to tech support.
Easwar
OriginLab.
Edited by - easwar on 10/05/2001 17:55:44 |
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Coolshark
Denmark
Posts |
Posted - 03/19/2007 : 1:48:06 PM
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A MODIFIED bessel function is not J or Y, so
How do you fit to a modified bessel function??
It is either a K or I... I really need these functions so if anyone has an answer please mail me!
\Martin
Edited by - Coolshark on 03/19/2007 1:48:42 PM |
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Mike Buess
USA
3037 Posts |
Posted - 03/19/2007 : 2:00:15 PM
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If you have Origin 7 or higher you can use the NAG libraries which contain several modified Bessel functions.
Origin C Language Reference > Global Functions > NAG Functions > NAG - Approximations of Special Functions
Mike Buess
Origin WebRing Member |
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Modified Bessel function in nonlinear curve fit