Re: Seeking further uidance on implementing a user defined equation in ROOT (More)

In my previouis mail I forgot to mention 2 problems   -you should provide a good error estimate for the bin contents of your histogram. The default being to use the sqrt(bin content) does not make much sense in your case. I used the option "w" that means use same weight=1 for all bins.

 -you should fix a few parameters. In my previous mail, all parameters were free. in the attachment
you will find an example where one of your parameters is fixed, you can add more.

Rene Brun

Russell Leslie wrote:
> Dear Rene,
>
> I seem to be missing some vital step in using a user defined equation
> to fit to a histogram.
>
> I am trying to use the function gks from the script gks.C (that you
> produced for me) as a fitting function for the Monte Carlo data that
> we produce from a FORTRAN program. I have attached a copy of a root
> file containing a typical set of such data (file MCGcalc.root).
>
> I have compiled your script (using the command ".x gks.C+") and
> produced a shared object gks_C.so.
>
> I have loaded gks_C.so (using the command ".L gks_C.so") and then
> tried to fit using various permutations of commands such as
>
> G2values.Fit("gks") but everything I have tried so far gives rise to
> messages similar to "Unknown function: gks" (with the occasional seg
> fault).
>
> I have been similarly unsuccessful using the FitPanel GUI.
>
> Any guidance you can give on what I might be doing wrong would be
> greatly appreciated.
>
> Regards
>
> Russell Leslie
> Nuclear Physics
> R.S.Phys.S.E.
> ANU
>
>
> ----- Original Message -----
> From: Russell Leslie <russell.leslie_at_gmail.com>
> Date: Friday, February 20, 2009 8:07 pm
> Subject: Fwd: [ROOT] Seeking guidance on implementing a user defined
> equation in ROOT
> To: u4504546_at_anu.edu.au
>
> >
> >
> > ---------- Forwarded message ----------
> > From: *Rene Brun* <Rene.Brun_at_cern.ch>
> > Date: Thu, Feb 19, 2009 at 7:16 PM
> > Subject: Re: [ROOT] Seeking guidance on implementing a user defined
> equation in ROOT
> > To: Russell Leslie <u4504546_at_anu.edu.au
> <javascript:main.compose('new', 't=u4504546_at_anu.edu.au')>>
> > Cc: roottalk_at_lxbuild091.cern.ch <javascript:main.compose('new',
> 't=roottalk_at_lxbuild091.cern.ch')>
> >
> >
> > Try the function gks.C in attachment
> > To run do:
> > root > .x gks.C+
> >
> > Rene Brun
> >
> > Russell Leslie wrote:
>
> > Dear all,
> > NOTE - message resent because I sent this originally from
> another account and it did not turn up on the roottalk list.
> > I am still feeling my way forward on ROOT, but I have found it
> to be a very useful tool-set.
> > One problem I am currently working on is to try to implement the
> following equations in ROOT (LaTex form of the equations below).
> >
> > $$
> > G_{k}(t) = e^{-\Lambda^{*} t}G_{k}^{(fluct.)}(t)+ \int_{0}^{t}
> \Lambda^{*} G_{k}^{(fluct.)}(t')\cdotp e^{-\Lambda^{*}
> t'}G_{k}^{(stat.)} (t-t')dt'
> > $$
> > Where Gk(stat) is give by the following equation
> > $$
> > G_{k}^{(stat.)} (t) = \left\langle \alpha_{k} \right\rangle + (
> 1 - \left\langle \alpha_{k}\right\rangle )e^{- \Gamma t}
> > $$
> > and Gk(fluct) is given by the this equation
> > $$
> > G_{k}^{(fluct.)}(t) = ( 1 - \lambda_{k}\tau_{c} )e^{ - \lambda
> _{k} t }
> > $$
> > The equations are from the manual for the Coulex code GOSIA and
> I want to use them as the fitting function for the output of a
> Monte Carlo simulation that we use.
> > I have had no problems producing the curves for Gk(stat) and
> Gk(fluct) - but I have not been able to implement the integral
> term in the Gk equation (the first equation above). The code I
> have so far is given below
> > {
> > //Calculate Gks
> > //parameter[0] = alpha_k
> > //parameter[1] = gamma
> > TF1 *Gks = new TF1("Gks","[0]+(1-[0])*exp(-[1]*x)",0,15);
> > Gks->SetParameters(0.221243,0.4);
> > //Calculate Gkf
> > //parameter[0] = lambda_k
> > //parameter[1] = tau_c
> > TF1 *Gkf = new TF1("Gkf","(1-[0]*[1])*exp(-[0]*x)",0,15);
> > Gkf->SetParameters(0.172,0.5);
> > //Calculate expLamba*t
> > //parameter[0] = 1 //parameter[1] = Lambda*
> > TF1 *eLst = new TF1("eLst","[0]*exp(-[1]*x)",0,15);
> > eLst->SetParameters(1,0.0345);
> > //Combine Gks and Gkf to for Gkcalc
> > TF1 *Gkcalc = new TF1("Gkcalc","Gkf*eLst*[0]*[1]",0,15); //
> This is the bit I can't get!!!!!!!!
> > //Create a canvas to draw Gkcalc
> > TCanvas *Gkcalc1 = new
> TCanvas("Gkcalc1","Gkcalc1",10,10,1400,1200);
> > //Draw and format Gkcalc
> > Gkcalc->Draw();
> > Gkcalc->SetLineWidth(2.0);
> > Gkcalc->SetLineColor(kBlue);
> > Gkcalc->GetXaxis()->SetTitle("time");
> > Gkcalc->GetYaxis()->SetTitle("G_{k}(t)");
> > Gkcalc->SetTitle("G_{k}(t) = e^{-#Lambda^{*}
> t}G_{k}^{(fluct.)}(t)+ #int_{0}^{t} #Lambda^{*}
> G_{k}^{(fluct.)}(t').e^{-#Lambda^{*} t'}G_{k}^{(stat.)} (t-t')dt' ");
> > Gkcalc->GetYaxis()->SetLabelFont(22);
> > Gkcalc->GetYaxis()->SetTitleFont(22);
> > Gkcalc->GetXaxis()->SetLabelFont(22);
> > Gkcalc->GetXaxis()->SetTitleFont(22);
> > //Add other lines
> > Gks->Draw("same");
> > Gks->SetLineWidth(2.0);
> > Gks->SetLineColor(kRed);
> > Gkf->Draw("same");
> > Gkf->SetLineWidth(2.0);
> > Gkf->SetLineColor(kGreen);
> > eLst->Draw("same");
> > eLst->SetLineWidth(2.0);
> > eLst->SetLineColor(kMagenta);
> > TLegend *legend = new TLegend(.75,.80,.95,.95);
> > legend->AddEntry(Gkcalc,"G_{k}(t)");
> > legend->AddEntry(Gks,"G_{k}^{(stat)}(t)");
> > legend->AddEntry(Gkf,"G_{k}^{(fluct)}(t)");
> > legend->AddEntry(Gks,"e^{-#Lambda^{*} t}");
> > legend->Draw();
> > }
> > My root details as as follows ROOT 5.18/00b
> (branches/v5-18-00-patches_at_22563 <mailto:branches
> <javascript:main.compose('new',
> 't=branches')>/v5-18-00-patches_at_22563>, Oct 19 2008, 22:04:00 on
> linuxx8664gcc4.3)
>
> > Any help or guidance you can give on this would be greatly
> appreciated.
> > Russell Leslie
> > Nuclear Physics
> > R.S.Phys.S.E.
> > ANU
>
> >
> >
>
>
> Russell Leslie
> Nuclear Physics
> R.S.Phys.S.E.
> ANU