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6.10/09
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tutorials
hist
cumulative.C File Reference
Tutorials
»
Histograms tutorials
Detailed Description
Illustrate use of the
TH1::GetCumulative
method.
#include <cassert>
#include <cmath>
#include "
TH1.h
"
#include "
TH1D.h
"
#include "
TCanvas.h
"
#include "
TRandom.h
"
TCanvas
*cumulative()
{
TH1
* h =
new
TH1D
(
"h"
,
"h"
, 100, -5., 5.);
gRandom
->
SetSeed
();
h->
FillRandom
(
"gaus"
, 1u << 16);
// get the cumulative of h
TH1
* hc = h->
GetCumulative
();
// check that c has the "right" contents
Double_t
* integral = h->
GetIntegral
();
for
(
Int_t
i = 1; i <= hc->
GetNbinsX
(); ++i) {
assert(std::abs(integral[i] * h->
GetEntries
() - hc->
GetBinContent
(i)) < 1e-7);
}
// draw histogram together with its cumulative distribution
TCanvas
* c =
new
TCanvas
;
c->
Divide
(1,2);
c->
cd
(1);
h->
Draw
();
c->
cd
(2);
hc->
Draw
();
c->
Update
();
return
c;
}
Author
M. Schiller
Definition in file
cumulative.C
.