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Re: Lorentzian on a baseline

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89193] Re: Lorentzian on a baseline
  • From: dflatin at rcn.com
  • Date: Thu, 29 May 2008 07:02:12 -0400 (EDT)
  • References: <g1j6g0$qne$1@smc.vnet.net>

On May 28, 4:52 am, fred.eng... at gmail.com wrote:
> I'm trying to fit a Lorentzian subtracted from a constant baseline,
> using findfit.
>
>  FindFit[rawdata, m1 - m2/((x - m3)^2 + m2^2), {m1, m2, {m3, 250}}, x,
>   MaxIterations -> 10000]
>
> Isn't working - either a totally flat horizantal line, or the
> subtracted 'Lorentzian' looks almost delta-function sharp. Help?
> Thanks!

I suspect that your main problem is that you need to provide initial
guesses for m1 and m2 in addition to m3.


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