KADD 2022 Laboratorium 1 EN

From Łukasz Graczykowski

Latest revision as of 12:47, 28 February 2022

Documentation

Documentation of the ROOT environment:

• main page: https://root.cern.ch/
• documentation of the development version (master): https://root.cern.ch/doc/master/
• documentation of the stable version (6.22): https://root.cern/doc/v622/
• documentation of the laboratory version (5.32.00): https://root.cern.ch/root/html532/ last version with the old C++ interpreter

Exercise

1. Write a macro, which:

• creates an object fun1 of type TF1 representing a sin(x) function (see class TMath)
• creates an object fun2 of type TF1 representing a cos(x) function
• creates a window with 4 panels (panel distribution 2x2) - see class TCanvas and method Divide
• draws the fun1 object on panel 1, fun2 on panel 2, and two functions simultaneously on panel 3
• changes the color of the line of function fun2 to blue - see method SetLineColor and class TColor

2. Let's imagine we throw a dice that is asymmetric. The table below summarizes the results:

We modify further the macro:

• let's create a histogram (see class TH1D) by filling each bin (which corresponds to each dice facet) with values from the table (number of throws) - the histogram should be plotted on panel 4
• create a plot, called graph (see class TGraph) according to values from the table.
• change the style of graph points (see method SetMarkerStyle and class TAttMarker)
• draw the graph in a separate window

Attention

• Attention! In order to run ROOT environment on your student account in the laboratory, you have to add the following lines (if they were not added already) to the file $HOME/.bashrc (they could had been added during the PTI class):

 export ROOTSYS=/opt/root
 export PATH=$PATH:$ROOTSYS/bin
 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$ROOTSYS/lib 

• the ROOT environment is installed separately on each computer - it is not available on the server
• in the ROOT environment we write macros, which have extensions .c, .C, .cpp, or .cxx
• a macro contains a C++ code interpreted line-by-line
• in principle, we do not need to include any libraries
• example 1:

{
    double x = 5;
    cout<<x<<endl;
}

• execution of a macro: start the environment (command root), type .x macro.C
• macro can also contain funkcje, example 2:

int macro()
{
    double x = 5;
    cout<<x<<endl;
    return 1;
}

• name of the macro must be the same as the name of the main function in the macro (in order to run it with the command .x macro.C)
• macros can contain more functions - during the macro execution the one which will be run is that which name corresponds to the macro name (the equivalent of the main function in standard C++)

Results

Plots:

• window 1

• window 2