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a.abc.b35
175 Posts |
 Posted - 06/09/2011 : 2:24:49 PM
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Origin Ver. and Service Release (Select Help-->About Origin): 8
Operating System: windows 7
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Hi, I have a fitting routine (say AFit) which is written in origin C (inside the fitting function organiser). I use this to fit my data with a single peak. Now what I want is, I want to fit two of AFit to the data. Its exactly like fitting a multi gauss fit/ lorentz fit. But I don't know how to write a fitting routine for a multi peak fit. Initially I thought to do the following :
Fit = AFit + AFit (assuming this is done same way in multi gauss/lorentz fit). But that seems to fail randomly ! Can anyone tell me / direct me to a web resource (in the forum or originlab website) where from I can learn to do that ?
Thanks in advance.
AB |
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Hideo Fujii
USA
1582 Posts |
Posted - 06/09/2011 : 3:21:48 PM
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Hi AB,
You can make a user-defined peak function when you define the function (which means your function has at least four parameters: y0 as the offset, X Center, X Width, and Amplitude/Area). You can read how to set your function as a peak function at:
http://www.originlab.com/www/helponline/Origin/en/UserGuide/Define_a_Peak_Function.html
(Or, in Origin help section: Peak Analyzer> Peak Analyzer Reference> Define a Peak Function.
Note that PFW category may be not improtant if you use the function in NLFit rather than in Peak Analyzer.)
Once you get a peak function, you should be use the function for replicas for multiple peaks.
At least the above should work in Origin 8.5.
--Hideo Fujii
OriginLab |
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a.abc.b35
175 Posts |
Posted - 06/10/2011 : 2:48:44 PM
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Hideo, I know how to make a peak function. The fitting routin (AFIT) is a peak function !
My question was how to make a multi-peak function...can anyone please answer that part ?
AB |
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easwar
USA
1964 Posts |
Posted - 06/10/2011 : 3:15:24 PM
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Hi AB,
What Hideo was pointing out was that you don't need to make a multi-peak fitting function. Once you have a function for fitting one peak, you can use the "Replica" feature in NLFit to fit multiple peaks in a dataset using that single-peak function.
To fit using replicas, do the following:
1> With your data plotted, open NLFit and select your function
2> Click Advanced in the left panel list under Settings tab
3> On the right panel set the number of replicas drop-down to (no. of peaks -1). So if you have two peaks set this to 1
4> Go to Parameters tab and assign values to the sets of parameters for each peak and then complete the fit
I just tried this in 8.0SR6 and 8.5.1SR1 and it worked fine. If you are unable to do this, contact tech support and send your fitting function file and your data/opj.
Easwar
OriginLab.
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a.abc.b35
175 Posts |
Posted - 06/10/2011 : 5:30:57 PM
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The Replica (with a + sign in front of it) is not active.
Am using SR6 Origin 8.0.
AB |
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easwar
USA
1964 Posts |
Posted - 06/10/2011 : 5:41:40 PM
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Hi AB,
The replica feature was grayed out in older versions only for surface fitting functions. From your posts it does not appear you have a surface fit function? As posted earlier, I tried 8.0SR6 and it works fine.
Please contact tech support so they can see what is going on with your version. As I said earlier, also send your FDF and data so we can try.
Easwar
OriginLab |
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a.abc.b35
175 Posts |
Posted - 06/10/2011 : 11:38:16 PM
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How do I contact them ? Please let me know.
AB |
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easwar
USA
1964 Posts |
Posted - 06/11/2011 : 09:18:37 AM
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Hi AB,
Click the "Send files to tech support" link on the top right of this page.
Attach your FDF and OPJ.
Easwar |
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a.abc.b35
175 Posts |
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Topic |
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Multi Peak Fit custom/user made fitting routin