TFile f("prehinv.root"); // prehinv.root is root file obtained from h2root
TH1F h1f("h1f","Higgs mass",100,0,200);  // an histogram
h10.Draw("Elep[0]");  // Gives a Funny plot
//7861 entries, Mean: 0, Rms: 0
h10.Draw("Elep");  // right plot
//16719 entries mean: 37.35 , Rms: 28.23 
//is sum of Elep vector ?
h10.Draw("Elep[0]"); // right plot !!! Why now ?
//7861 entries, Mean: 46.05, Rms: 33.9
Char_t*  Zmass2 = "2*Elep[0]*Elep[1]*(1-(sin(Tlep[0])*cos(Plep[0])*sin(Tlep[1])*cos(Plep[1])+sin(Tlep[0])*sin(Plep[0])*sin(Tlep[1])*sin(Plep[1])+cos(Tlep[0])*cos(Tlep[1])))";
Char_t Hmass[300];
sprintf(Hmass,"sqrt(Encm*Encm+%s-2.*Encm*(Elep[0]+Elep[1]))>>%s",Zmass2,"h1f")
h10.Draw(Hmass);
//This error message is done:
//*ERROR 26 : 
// Unknown name : "Elep[0]"
//Why ?
//and now 
h10.Draw("Elep[0]");
//gives the same error !
//*ERROR 26 : 
// Unknown name : "Elep[0]"
Here you can find informations about Elep
*..................................................................................*
*Branch  :Elep      : Elep[Nlpt]/F                                                 *
*Entries :     7861 : Total  Size =     97072 bytes  File Size  =      61622 bytes *
*Baskets :        4 : Basket Size =     32000 bytes  EvOffsetLen=       2000       *
*        :          : Branch compression factor =   1.58                           *
*..................................................................................*
Thank you.
==========================
                    __ | 
Patrice Lebrun     |  ||
HEE1              _|__||
IPN de Lyon        |   |__ 
tel: 72 44 84 43   |at       
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