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a.abc.b35
175 Posts |
 Posted - 07/07/2011 : 4:36:23 PM
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Origin Ver. and Service Release (Select Help-->About Origin): 8.5.1
Operating System:win 7
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Hi I have a fitting function which involves two definite integrals from 0 to 1 and -2 to 2 (say). I have written a nlfit origin C code (using NAG library) for that and been using it for a while. IT works great but is slow ! Now I have recently noticed the Voigt function,viz,
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which is written in origin as below (accessed from NLFIT window, by F9 button):
quote:
y = y0 + (A*2*ln(2)*wL)/(Pi^1.5*wG^2) * integ( exp(-t^2) / ((sqrt(ln(2))*wL/wG)^2+(sqrt(4*ln(2))*(x-xc)/wG-t)^2) )
After seeing this, and also the fastness of the Voigt fit, I want to change my fitting function in this format, especially, I want to use the quote:
integ
function but in my case limits are 0 to 1 and -2 to 2 instead of -infinity to +infinity, as in Voigt.
Can anyone tell me how to use that function for a definite integral or if there is something else like this ? Also a web link to origin help for help on this function will be very much appreciated.
AB |
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Penn
China
644 Posts |
Posted - 07/07/2011 : 9:58:39 PM
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Hi AB,
Maybe you can refer to this tutorial.
Penn |
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a.abc.b35
175 Posts |
Posted - 07/07/2011 : 11:07:59 PM
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Penn, I have used the above tutorial to write my integration function and is using it for a while now. But I recently saw the fastness of the integ function in Voigt and wanted to use that intead of the NAG integration I have made. But am having difficulty in locating even a help file for it. Hope the question is clear now.
AB |
Edited by - a.abc.b35 on 07/08/2011 02:17:55 AM |
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minimax
351 Posts |
Posted - 07/08/2011 : 04:10:05 AM
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Hi AB,
In fact, the integ function in Voigt is not a real function.
It is simply a notation to indicate the integral.
Sorry for the confusion; we should have add some comments in that function to avoid misleading.
As to the slowness, we will check and response to you soon.
Max
OriginLab Technical Support |
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a.abc.b35
175 Posts |
Posted - 07/08/2011 : 8:50:31 PM
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@ minimax : can you give me some info about it so that I can use it in my case. Writing a fitting function involving integration then becomes a whole lot easier !
AB |
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a.abc.b35
175 Posts |
Posted - 07/12/2011 : 12:32:39 PM
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Anyone listening ?
AB |
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larry_lan
China
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Posted - 07/12/2011 : 11:22:44 PM
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Hi AB:
The most effective way is define an External DLL fitting function, and call GNU Scientific Library to do integration in the DLL. We are now fine tuning the example, and will put it on File Exchange later. Now, I have sent this example to the email address in you profile.
Thanks
Larry
OriginLab |
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Topic |
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Voigt like fitting function