Rene Brun
{
#include <iostream.h>
// estimate range for plot
TF1 *func = new TF1("func","exp(-0.5*((x-11.0)/0.1)^2)");
TH1F* histo = new TH1F("histo","Histogram of Gluino Condensate",
300,10,12);
histo->FillRandom("func",1024*1024);
cout << "using data in range " << " "
<< histo->GetMean() << " "
<< histo->GetRMS()<< endl;
printf("%f\n", histo->GetMean());
printf("%f\n", histo->GetRMS());
}
Joerg.Westphalen@desy.de wrote:
>
> Hi everbody,
>
> after the latest update (to 2.00/12) none of my root programs worked
> properly anymore. A few hours of headache let me to the conclusion that
> something may be wrong with the GetRMS method of class TH1.
>
> Here is a small program producing wrong results:
>
> //
> // jw 10/98
> //
> //
>
> #include <TROOT.h>
> #include <TApplication.h>
> #include <TRint.h>
> #include <TF1.h>
> #include <TH1.h>
>
> extern void InitGui();
> VoidFuncPtr_t initfuncs[] = { InitGui, 0 };
>
> TROOT root("correlation", "CORRELATION", initfuncs);
>
> int main(int argc, char **argv)
> {
> int local_argc(1);
>
> //TApplication* theApp = new TApplication("App", &local_argc, argv);
> TRint *theApp= new TRint("Rint", &local_argc, argv, 0, 0);
>
> // estimate range for plot
> TF1 *func = new TF1("func","exp(-0.5*((x-11.0)/0.1)^2)");
> TH1F* histo(new TH1F("histo","Histogram of Gluino Condensate",
> 300,10,12));
> histo->FillRandom("func",1024*1024);
>
> cout << "using data in range " << " "
> << histo->GetMean() << " "
> << histo->GetRMS()<< endl;
>
> printf("%f\n", histo->GetMean());
> printf("%f\n", histo->GetRMS());
>
> theApp->Run();
>
> delete theApp;
>
> return 0 ;
> }
>
> Compiling this (with gcc or egcs) and executing results in:
>
> [...]
> *******************************************
> * *
> * W E L C O M E to R O O T *
> * *
> * Version 2.00/12 9 October 1998 *
> * *
> * You are welcome to visit our Web site *
> * http://root.cern.ch *
> * *
> *******************************************
>
> CINT/ROOT C/C++ Interpreter version 5.13.75, Sep 23 1998
> Type ? for help. Commands must be C++ statements.
> Enclose multiple statements between { }.
>
> using data in range 28104 1.04858e+06
> 28104.000000 <---!!!!!!!!!!!!!
> 1048576.000000
> root [0] printf("%f\n", histo->GetRMS());
> 0.099994 <---!!!!!!!!!!!!!
> root [1]
>
> When drawing (histo->Draw()) also RMS=0.0999939 shows up.
>
> Whats wrong with my program, or is this is a bug in root ?
> Is this a local problem with our installation here ?
>
> Bye,
>
> Joerg Westphalen
>
> PS. In my original programs i am using Fill(x,w), not FillRandom(),
> producing the same problem.
>
> --
> --------------------------------------------------------------------
> Joerg Westphalen Email: Joerg.Westphalen@desy.de
> DESY - Theorie - Julius-Brecht-Str. 7
> Notkestr. 85, 22603 Hamburg 22609 Hamburg
> Tel: 040-8998-3605 (buero) Tel: 040-8078007 (privat)
> Fax: 040-8994-3605
> Geb. 2a, Zi. 409
> --------------------------------------------------------------------