Problem in drawing variable divided by some number

Dear Experts,

Bslxysig is variable in a root file(tree). I want to draw Bslxysig/1367.144. How to draw, could you please tell me? I have pasted the snippet of my code here.

TChain *ch = new TChain("tree");
 ch>Add("/home/deepak/BsToPhiMuMu/MC/mumuphisel/cut1mcnogen/sel_BsToPhiMuMu_mumuphi_cut1_mc_nogen_mc.nogen_cut1_*.root");
  TTree *tr1 = ch;
TH1F *h1 = new TH1F("h1", "K^{+} Transverse momentum",100,7.0,100.0);
  tr1->Draw("(Blxysig/1367.144)>>h1");

Thanks,
Deepak

tr1->Draw("(Blxysig/1367.144)>>h1");

This is correct. The range along the X axis will be the one of Blxysig/1367.144

If you want to divide the distribution by 1000 you can fille the histogram h1 as you did and then divide h1 by 1000.

You can also try to put a weight of 0.001 … but that might not be what you want.

tr1->Draw("(Blxysig/1367.144)", "0.001", "hist");
tr1->Draw("(Blxysig/1367.144)>>h1"); 

is not working. It is giving empty canvas.

Thanks,
Deepak

Try (see the x-axis range of the drawn histogram and compare to your “h1”):

ch->Draw("Blxysig/1367.144"); // note: "ch", not "tr1"

I tried this and it is giving same thing as before(empty canvas with no.of entries). there is no distribution. For comparing the x-axis range, I am fixing h1 as (7,100) and the plot shows x-axis range as (7,100).

Thanks,
Deepak

Try:

ch->Print();
std::cout << ch->GetEntries() << std::endl;

It’s giving details(size,variablename) of all variables in that tree.

Thanks,
Deepak

Post the output here for inspection.

Here is the output.

Processing Bslxysig.cc...
******************************************************************************
*Chain   :tree      : /home/deepak/BsToPhiMuMu/MC/mumuphisel/cut1mcnogen/sel_BsToPhiMuMu_mumuphi_cut1_mc_nogen_mc.nogen_cut1_s0.root *
******************************************************************************
******************************************************************************
*Tree    :tree      : tree                                                   *
*Entries :  1000000 : Total =       181002935 bytes  File  Size =    2790382 *
*        :          : Tree compression factor =   1.00                       *
******************************************************************************
*Br    0 :Mumumass  : Mumumass/D                                             *
*Entries :  1000000 : Total  Size=    8044980 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    1 :Mumumasserr : Mumumasserr/D                                        *
*Entries :  1000000 : Total  Size=    8046498 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    2 :Phimass   : Phimass/D                                              *
*Entries :  1000000 : Total  Size=    8044474 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    3 :Kmpt      : Kmpt/D                                                 *
*Entries :  1000000 : Total  Size=    8042956 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    4 :Kppt      : Kppt/D                                                 *
*Entries :  1000000 : Total  Size=    8042956 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    5 :Kmtrkdcasigbs : Kmtrkdcasigbs/D                                    *
*Entries :  1000000 : Total  Size=    8047510 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    6 :Kptrkdcasigbs : Kptrkdcasigbs/D                                    *
*Entries :  1000000 : Total  Size=    8047510 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    7 :Bmass     : Bmass/D                                                *
*Entries :  1000000 : Total  Size=    8043462 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    8 :Bpt       : Bpt/D                                                  *
*Entries :  1000000 : Total  Size=    8042450 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br    9 :Beta      : Beta/D                                                 *
*Entries :  1000000 : Total  Size=    8042956 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   10 :Bphi      : Bphi/D                                                 *
*Entries :  1000000 : Total  Size=    8042956 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   11 :Bvtxcl    : Bvtxcl/D                                               *
*Entries :  1000000 : Total  Size=    8043968 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   12 :Blxysig   : Blxysig/D                                              *
*Entries :  1000000 : Total  Size=    8044474 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   13 :Bcosalphabs : Bcosalphabs/D                                        *
*Entries :  1000000 : Total  Size=    8046498 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   14 :Bcosalphabs2d : Bcosalphabs2d/D                                    *
*Entries :  1000000 : Total  Size=    8047510 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   15 :Bctau     : Bctau/D                                                *
*Entries :  1000000 : Total  Size=    8043462 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   16 :Q2        : Q2/D                                                   *
*Entries :  1000000 : Total  Size=    8041944 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   17 :dimupt    : dimupt/D                                               *
*Entries :  1000000 : Total  Size=    8043968 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   18 :dimueta   : dimueta/D                                              *
*Entries :  1000000 : Total  Size=    8044474 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   19 :CosThetaL : CosThetaL/D                                            *
*Entries :  1000000 : Total  Size=    8045486 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   20 :CosThetaK : CosThetaK/D                                            *
*Entries :  1000000 : Total  Size=    8045486 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   21 :PhiAng    : PhiAng/D                                               *
*Entries :  1000000 : Total  Size=    8043968 bytes  All baskets in memory   *
*Baskets :      250 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
*Br   22 :Triggers  : Triggers/I                                             *
*Entries :  1000000 : Total  Size=    4022722 bytes  All baskets in memory   *
*Baskets :      125 : Basket Size=      32000 bytes  Compression=   1.00     *
*............................................................................*
******************************************************************************

Thanks,
Deepak

So, you should get histograms with 1000000 entries.
Try to print the first 10 entries (see what values you get):

ch->Scan("Blxysig", "", "", 10, 0);

I am pasting the output.

 Processing Bslxysig.cc...
************************
*    Row   *   Blxysig *
************************
*        0 *         0 *
*        1 *         0 *
*        2 *         0 *
*        3 *         0 *
*        4 *         0 *
*        5 *         0 *
*        6 *         0 *
*        7 *         0 *
*        8 *         0 *
*        9 *         0 *
************************
Info in <TCanvas::Print>: file bslxysig.png has been created

Well, try:

ch->Scan("Blxysig", "Blxysig != 0");

It’s giving nonzero values as below.

Processing Bslxysig.cc...
************************
*    Row   *   Blxysig *
************************
*      297 * 91.087971 *
*      333 * 69.225149 *
*      480 * 72.621874 *
*      600 * 22.015388 *
*      793 * 166.70694 *
*      853 * 27.881502 *
*      919 * 21.451616 *
*     1088 * 29.436973 *
*     1144 * 22.077651 *
*     1507 * 24.498037 *
*     1597 * 12.849612 *
*     1780 * 30.894640 *
*     1783 * 12.644404 *
*     1791 * 42.579906 *
*     1901 * 33.359760 *
*     1947 * 17.262691 *
*     1962 * 79.138282 *
*     2008 * 14.660279 *
*     2072 * 37.603640 *
*     2186 * 42.417438 *
*     2222 * 41.521340 *
*     2386 * 93.572485 *
*     2804 * 27.309963 *
*     3026 * 131.57564 *
*     3545 * 15.305382 *

Thanks,
Deepak

Try:

ch->Draw("Blxysig/1367.144", "Blxysig != 0");

BTW. When you post “output” or “source code” here, do remember to enclose them into two lines which contain just three characters ``` (see how your posts have been edited above).

It’s giving the distribution as below.bslxysig

Thanks,
Deepak

So, you should also get a correct plot with 1000000 entries when you try (just the first bin at x = 0 will be higher):

ch->Draw("Blxysig/1367.144");
gPad->SetLogy(1);

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