| T O P I C R E V I E W |
| vanguard |
Posted - 07/13/2001 : 02:10:44 AM
Hi,
I am a newbie to Origin. I have data that needs to be fitted to a Lorentzian and 2 Guassian curves. Following which, I need to extract the width of these fitted curves. How may I do it?
Would appreciate any help on this. Thank you. |
| 5 L A T E S T R E P L I E S (Newest First) |
| rtoomey |
Posted - 08/23/2001 : 3:52:00 PM
So were you able to get this to work using the Nonlinear Curve Fitter in Origin?
If not, you should strongly consider getting our Peak Fitting Module. The PFM can:
1. fit each individual peak in your data to a different function quickly and with minimal effort,
2. auto-initialize peak heights and centers,
3. display individual peak curves,
4. and much more.
If you would like to try the demo version of the PFM, go to the PFM demo download page. Note: The PFM demo requires Origin 6.1 SR3 or higher. The Origin 6.1 demo can also be used.
- rtoomey
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| vanguard |
Posted - 07/13/2001 : 9:27:00 PM
The first link is to the Origin data file... u can get it direct here at:
http://sg.y42.briefcase.yahoo.com/vanguardsheet
It is the data that I wish to fit to. My Origin version is 5.
Would appreciate more clarification or an example on what I wish to do..
thanks!
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| rtoomey |
Posted - 07/13/2001 : 4:17:08 PM
In the nonlinear curve fitter, you can define a user-defined fitting function that is made up of a series of functions. Furthermore, Origin already has built-in gaussian and lorentzian functions. They are:
gauss(x,y0,x0,w,A)
lorentz(x,y0,x0,w,A)
where:
w = 2*(standard deviation of the gaussian distribution) or approx. 0.849 * FWHM for the gaussian function
w = FWHM for the lorentzian function
So, all you have to do is define a function using our built-in gaussian and lorentzian functions. Here's how the Define New Function page of the fitter might be filled out:
| Name | (Anything you want) | | Type | User-defined | | Number of Parameters | 13 | | User Defined Param. Names | Checked | | Parameter Names | y00,y01,x01,w1,A1,y02,x02,w2,A2,y03,x03,w3,A3 | | Independent Var | x | | Dependent Var | y | | Definition | y = y00 + gauss(x,y01,x01,w1,A1) + lorentz(x,y02,x02,w2,A2) + gauss(x,y03,x03,w3,A3) | | Form | Equations |
Some things to remember when fitting:
- Set y01#, y02, and y03 to 0 and fix them (i.e. uncheck the associated Vary? check boxes) so that the only parameter effecting the baseline is y00.
- The x0# parameters (x01, x02, x03) represent the center for each peak. You should make sure your initial values for these three parameters are reasonably good since they have a great effect on the fit.
- The A# parameters (A1, A2, A3) represent the area under each peak for Gauss and Lorentz. There is a different form of the Gaussian function called GaussAmp. The paramter A represents amplitude in that function. If you want to use that one in place of the Gauss function, the form is the same (except for the name of course!): GaussAmp(x,y0,xc,w,A).
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| Mike Buess |
Posted - 07/13/2001 : 11:48:12 AM
There is something wrong with the first URL. I get this error message: "You must supply a local referer to get URL '/users/bf1bc8de/bc/Origin+Data+File.opj?bcR8vn7Aq1.TNUxo' from this server."
It might also be useful to tell us which version of Origin you are using.
Mike Buess
Origin WebRing Member
P.S. Has something happened to word wrapping in this forum?
Edited by - Mike Buess on 07/13/2001 11:49:51 |
| vanguard |
Posted - 07/13/2001 : 02:25:04 AM
Here's my origin data file that I need to fit the 2 gaussian and 1 lorentzian curve to:
http://us.f1.yahoofs.com/users/bf1bc8de/bc/Origin+Data+File.opj?bcR8vn7Aq1.TNUxo
To help clarify what I am trying to do, here's a picture:
http://sg.y42.briefcase.yahoo.com/bc/vanguardsheet/vwp?.dir=/&.dnm=fitting.gif&.src=bc&.view=l&.done=http%3a//sg.y42.briefcase.yahoo.com/bc/vanguardsheet/lst%3f%26.dir=/%26.src=bc%26.view=l
Sincerely, hope that someone can help... Thank you and have a nice day.
(I am contactable at vanguardsheet@yahoo.com.sg for further queries) |
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