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karasek
Posts |
 Posted - 10/13/2005 : 06:12:19 AM
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Origin Version (Select Help-->About Origin): Origin 7SR1
Operating System:Windoes XP
Does anybody know how to perform in Origin fitting of convolution of two user defined function: gaussian A*exp(-((x-xc)/wG)^2) and Lorentz 1/Pi*wL/(wL^2+(x-xc)^2). The independent variable is x, the dependent is y and A, wL, wG, xc are the parameters to be fitted. I know that convolution is defined by the following equation:
f(x)=Integral[f1(x-t)*f2(t)dt]
But I do not know how to do a convolution in Origin and then fitting convoluted function to my data
I will be very grateful for help
Thank you very much |
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easwar
USA
1964 Posts |
Posted - 10/13/2005 : 1:40:49 PM
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Hi,
If you are looking only for a line shape/peak function that is a convolution of the gaussian and lorentzian functions, try the Voigt function in the Peak Functions category in NLSF.
If you want a general mechanism to perform convolution while fitting, that will involve programming by calling convolution function during fitting.
Easwar
OriginLab
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karasek
Posts |
Posted - 10/14/2005 : 08:05:47 AM
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Hi,
thanks for yor reply Easwar
I know that Voigt function is implemented in Origin but I need
a general mechanism to perform convolution while fitting because I want to define my own lorentzian and gaussian. Can you tell me how to do this, I mean how this program should looks like. I am not so good at programming. How to involve programming by calling convolution function during fitting.
Thanky very much |
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Kitkit Zhang
China
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Posted - 10/18/2005 : 05:58:53 AM
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Hi,
We have found a solution to your problem. Please send a mail to tech@originlab.com , so that we can send the FDF file to you.
Edited by - Kitkit Zhang on 10/18/2005 06:09:37 AM |
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CHelixN
Denmark
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Posted - 11/08/2005 : 10:17:35 AM
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Hi,
I am performing multipeak fitting. The options now are Gaussian (G) or Lorentzian (L). I would like to combine these two as A*G+(1-A)*L where A is a fitting parameter being the fraction of Gaussian character and A is the same for all peaks. Please let me know how I can do this. Also it would be nice if one could do multi Voigt peak fitting!
Cheers.
Helix |
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Mike Buess
USA
3037 Posts |
Posted - 11/09/2005 : 10:58:52 AM
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If G and L share the same center (xc) and offset (y0) then Origin's PsdVoigt1 or PsdVoigt2 peak function might work. Otherwise you'll need to define your own function as described in the Origin Reference. In either case you can fit multiple peaks using replicas.
Mike Buess
Origin WebRing Member |
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Topic |
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fitting convoluted function