[R] Pseudo-Voigt fit

From: <ppancoska_at_notes.cc.sunysb.edu>
Date: Sat 27 Aug 2005 - 05:08:38 EST

Hi, I am sorry for this question, but I am trying to speed up an application....
I will need to fit many x-y data sets (input from text files) to 4-parameter Pseudo-Voigt peak function.
Until now I used SigmaPlot macro to do it (enclosed just in case...)

peaksign(q) = if(total(q)>q[1], 1, -1)
xatymin(q,r) = xatymax(q,max(r)-r)
[Parameters]

a = if(peaksign(y)>0, max(y), min(y)) ''Auto {{previous: 60.8286}}
b = fwhm(x,abs(y))/2 ''Auto {{previous: 0.656637}}
c = .5 ''Auto {{previous: 6.82973e-010}}
x0 = if(peaksign(y)>0, xatymax(x,y), xatymin(x,y)) ''Auto {{previous: 3.19308}}

[Equation]

f = a*(c*(1/(1+((x-x0)/b)^2))+(1-c)*exp(-0.5*((x-x0)/b)^2))

fit f to y

 (manageable for ~100), but it looks like the next project would need to process ~1000 member sets.

I am not as familiar with R to find the right info (although I can use R in general).

I am also nearly sure that there should be a solution to this task "out there" ready to be modified...

Could you be so kind and direct me please to the right package or web-site with examples?

Thank you very much

Dr. Petr Pancoska
Department of Pathology
SUNY Stony Brook, NY 11794
phone: (631)-444-3030


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