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hprod.C File Reference

Detailed Description

Histogram producer script.

This script creates a memory mapped file and stores three histogram objects in it (a TH1F, a TH2F and a TProfile). It then fills, in an infinite loop (so use ctrl-c to stop this script), the three histogram objects with random numbers. Every 10 fills the objects are updated in shared memory. Use the hcons.C script to map this file and display the histograms.

// Create a new memory mapped file. The memory mapped file can be
// opened in an other process on the same machine and the objects
// stored in it can be accessed.
mfile = TMapFile::Create("hsimple.map", "RECREATE", 1000000,
"Demo memory mapped file with histograms");
// Create a 1d, a 2d and a profile histogram. These objects will
// be automatically added to the current directory, i.e. mfile.
hpx = new TH1F("hpx","This is the px distribution",100,-4,4);
hpxpy = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4);
hprof = new TProfile("hprof","Profile of pz versus px",100,-4,4,0,20);
// Set a fill color for the TH1F
// Print status of mapped file
// Endless loop filling histograms with random numbers
Float_t px, py, pz;
int ii = 0;
while (1) {
pz = px*px + py*py;
if (!(ii % 10)) {
mfile->Update(); // updates all objects in shared memory
if (!ii) mfile->ls(); // print contents of mapped file after
} // first update
float Float_t
Definition RtypesCore.h:57
#define gROOT
Definition TROOT.h:407
R__EXTERN TRandom * gRandom
Definition TRandom.h:62
1-D histogram with a float per channel (see TH1 documentation)}
Definition TH1.h:577
2-D histogram with a float per channel (see TH1 documentation)}
Definition TH2.h:258
static TMapFile * Create(const char *name, Option_t *option="READ", Int_t size=kDefaultMapSize, const char *title="")
Create a memory mapped file.
Profile Histogram.
Definition TProfile.h:32
virtual void Rannor(Float_t &a, Float_t &b)
Return 2 numbers distributed following a gaussian with mean=0 and sigma=1.
Definition TRandom.cxx:500
Fons Rademakers

Definition in file hprod.C.