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

In attachment you will find a new file gks2.C where I have changed the logic to perform the fit.
Please check the formula (not totally sure of my changes). You should be able to understand what I did.
root > .x gks2.C+

Rene

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