**Next message:**Troy D. Straszheim: "Re: [ROOT] cout << string ? (cintdlls/string.so build failure)"**Previous message:**Mike Williams: "[ROOT] htmldoc generation question"**In reply to:**Ahmed Al-Jamel: "Re: [ROOT] statistical error of Intergation"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

Yep. That makes it a log easier esp. if you're going to do the fits a bunch of times. ----- Original Message ----- From: "Ahmed Al-Jamel" <ahmed1@rcf.rhic.bnl.gov> To: "Arthur E. Snyder" <snyder@slac.stanford.edu> Cc: <ahmed_jamel@yahoo.com>; <roottalk@pcroot.cern.ch> Sent: Sunday, February 29, 2004 7:25 PM Subject: Re: [ROOT] statistical error of Intergation > > Thank you Arthur. What I really did to avoid this is to re-define my > Gaussian function so that the constant N is now the number of J/psis: > > Gassian = N/srqrt(2*pi*sigma) > EXP[-0.5((x-\bar x)/sigma)^2]. > > Then, we have the statistcial error on N is the statistical error of > the J/psi counts., which is COMPUTED directly by root and shown on the > statistical window of the Canvas. Does this sound correct?. > > Sorry if my questions look elementary, but this is the first of my work > with root. > > Best Regards, Ahmed > > Arthur E. Snyder wrote: > > >This not really a root problem ... just propagation of errors. The peak P > >(par[0])) is related to area by A=P*sigma*sqrt(2pi) (no integral function > >needed!), so given error matrix on P and sigma it easy to compute error on > >A. > > > > > >----- Original Message ----- > >From: "Ahmad" <ahmed_jamel@yahoo.com> > >To: <roottalk@pcroot.cern.ch> > >Cc: <ahmed1@rcf.rhic.bnl.gov> > >Sent: Friday, February 27, 2004 6:18 PM > >Subject: [ROOT] statistical error of Intergation > > > > > > > > > >>Dear Rooters, > >> > >> I am new to the list, and I have the following which I coud not figure > >> > >> > >out > > > > > >>how to do it under root. I'm fitting my J/psi peaks by a Gaussian function > >> > >> > >: > > > > > >>f=N*Exp[-(x-\bar{x})^2/2 sigma^2]. Then I utilized the function > >>Integral(min,max) to find the area or the number of counts under this fit. > >>. > >>. > >>. > >>n[j]->Fit("Gaus","R"); > >>G->SetParameters(par[0],par[1],par[2]); > >>float mean = par[1]; > >>float sigma = par[2]; > >>float mlo = mean-3.0*sigma; > >>float mhi = mean+3.0*sigma; > >>cout <<mean<<" and "<<sigma<<" and " <<mlo<<"and "<<mhi<<endl; > >>float binw = n[j]->GetBinWidth(1); > >>double COUNTS = G->Integral(mlo,mhi)/binw; > >>. > >>. > >>. > >> > >> > >>I need to know how to find the statistical error of the integral, i.e. > >> > >> > >"COUNTS" > > > > > >>in root. > >> > >>Thank you very much > >> > >>Ahmed. > >> > >> > >> > >> > >> > >>===== > >>"EAST OR WEST, HOME IS BEST". > >> > >> Ahmed Al-Jamel > >> Physics Department(http://www.physics.nmsu.edu) > >> New Mexico State University > >> Box 30001, MSC 3D > >> Las Cruces, NM 88003-8001 > >> Tel (off): (505)-646-7614. > >> http://www.feynman.nmsu.edu > >> http://www.phenix.bnl.gov/phenix/WWW/publish/ahmed1/ > >> > >>__________________________________ > >>Do you Yahoo!? > >>Get better spam protection with Yahoo! Mail. > >>http://antispam.yahoo.com/tools > >> > >>

**Next message:**Troy D. Straszheim: "Re: [ROOT] cout << string ? (cintdlls/string.so build failure)"**Previous message:**Mike Williams: "[ROOT] htmldoc generation question"**In reply to:**Ahmed Al-Jamel: "Re: [ROOT] statistical error of Intergation"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

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