Hi,
You will need to define an new FDF that combines the peak equations. So for example if you have a dataset say with one gaussian peak and one lorentzian peak, you could define the FDF as:
y=gauss(x,y0,xc1,w1,A1) + lorentz(x,y0,xc2,w2,A2);
where y0 is a common offset (does not have to be), and xc1, w1, A1 are parameters for the gaussian and xc2, w2, A2 are parameters for the lorentzian.
Set the Form drop-down on the function definition page to "Y-Script" (in later versions, uncheck the Origin C check box and then change the drop-down).
If you have more than a couple of peaks and want to consider more than just two possible peak functions, the above obviously becomes tedious. Then you may want to look at the Peak Fitting Module in which you can fit much more than two peaks, and also arbitrarily assign different peak functions to each peak in the data etc.
Easwar
OriginLab
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Gauusian+Loentzian fit
Posted - 09/28/2005 : 10:12:33 AM
