[ROOT] Bad representation of fitted function to TGraph.

From: Remi Mommsen (remigius.mommsen@cern.ch)
Date: Tue Nov 18 2003 - 05:53:36 MET 

Dear rooters,

I have a problem with the representation of a fitted function to 
TGraph. I use a code which boils down to the following macro:

macro tgraph.C:
====================================================================
#if !defined( __CINT__ ) || defined( __MAKECINT__ )
#include "TGraph.h"
#include "TF1.h"
#include "TMath.h"
#endif

Double_t sine(Double_t *x, Double_t *par) {
   return par[0]*TMath::Sin(par[1]*x[0]);
}

TF1* getFunction() {
   TF1* func = new TF1("sine",sine,0,7,2);
   return func;
}

Bool_t tgraph() {
   Double_t x[5] = {0,1.57,3.14,4.71,6.24};
   Double_t y[5] = {0,1,0,-1,0};

   TGraph* graph = new TGraph(5, x, y);
   graph->SetMarkerStyle(8);
   graph->Draw("ap");

   Double_t par[2] = {1,1};

   TF1* func2 = getFunction();               // <--- causes the problem
   TF1* func = getFunction();
   func->SetParameters(par);
   graph->Fit(func);

   return true;
}
====================================================================

The result of this macro is okay if I interpret it in root (i.e. .x 
tgraph.C), but if I compile it in root (i.e. .x tgraph.C+) I get the 
function plotted in fill mode (see attached gif file). None of the 
goption does affect the way it is plotted. The problem vanishes if I 
remove the line defining func2.

I see this problem with root 3.05/07 and 3.10/01 on both Mac OS X and 
RH9, however it seems to be okay for root 3.02/07 on RH7.2.

Thanks for your help.

Cheers,
		Remi
c1.gif --------------------------------------------------------------------- Truth decays into beauty, while beauty soon becomes merely charm. Charm ends up as strangeness, and even that doesn't last, but up and down are forever. (Anonymous) ********************************************************************* Remigius K. Mommsen e-mail: mommsen@slac.stanford.edu University of California, Irvine URL: http://cern.ch/mommsen c/o SLAC voice: ++1 (650) 926-3595 2575 Sand Hill Road #35 fax: ++1 (650) 926-3882 Menlo Park, CA 94025, US home: ++1 (650) 233-9041 *********************************************************************

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