[ROOT] Some doubt in ROOT

From: Sudeep Chatterji (Sudeep.Chatterji@cern.ch)
Date: Fri Feb 06 2004 - 10:34:59 MET


Hi Rooters,
  We are going to organize a ROOT Tutorial in University of Delhi, India in the coming week. I have some questions regarding ROOT which are listed below.  Kindly help us in clearing our doubts.                                                                                                              

1) When we use Legend, why we use "p" option for Graphs and "f" and "l" option for functions.                                                       
2) What is Cycle number in the list of objects, when we use f.Map() command.                                                                      
3) What is the diffrence between memory and disk?                        
4) When we close a file, the objects in it are erased. Will the objects be erased both in disk as well as memory?                                   
5) In the Chapter on Fitting Histograms, in the Section "Example:Fitting Multiple Sub Ranges" what does the following line mean                     total=new TF1("mstotal","gaus(0)+gaus(3)+gaus(6)",85,125)                                                                                          
Please clarify the meaning of "gaus(0)+gaus(3)+gaus(6)".
6) In the Chapter on Tree, in the first example on "staff at CERN" what is the significance of following commands
 sscanf(&line[0],"%d%d%d%d",.....);
 sscanf(&line[13],"%d%d%d%d",....);
 sscanf (&line[24],"%d%d%d",...);


Are we reading data from line#0 to line #12, then from line #13 to 24? If so then how do we know that the data for four variables ends on line 12?


6) In the Chapter on Physics Vectors under section TRotation, what is the meaning of the following command
Double_t xx=r(0,0)
What is the meaning of (0,0) in the above command?

Thanks in advance,
With best regards,
Sudeep Chatterji



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