Voigt fit parameters

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Thu, 02/20/2014 - 10:41 am

I am trying to use fVoigtFit on some data and cannot make sense of the returned fit coefficients and how to properly choose initial guesses. I have read notes TN026 but I still cannot see the relationship between the initial fit parameter guesses and the output fit coefficients. I have attached an example in case it helps.
The initial guesses were:
w0=0
w1=1.5
w2=2
w3=0
w4=2



Thanks,
Leo Graph5.pdf
The only code I use is to load a data file and plot it. Then I use the analysis tab, curve fitting, fVoigtfit and input the initial guesses to get the fit.

February 20, 2014 at 01:19 pm - Permalink

One possible approach would be to use the Multipeak Fit package, even though you're fitting just one peak. It makes sense of those peculiar coefficients for you. See the demo: File->Example Experiments->Curve Fitting->Multi-peak fit 2 Demo.pxp.

The picture of your data looks like it has some baseline and small superposed peaks off to the left as well as the big main peak, so maybe Multipeak Fit will be of more help than just to make sense of the Voigt coefficients.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

February 21, 2014 at 09:37 am - Permalink