Update to pythi8.170

[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8170 / examples / main24.cc

diff --git a/PYTHIA8/pythia8170/examples/main24.cc b/PYTHIA8/pythia8170/examples/main24.cc
new file mode 100644 (file)
index 0000000..677b79a
--- /dev/null
+++ b/PYTHIA8/pythia8170/examples/main24.cc
@@ -0,0 +1,77 @@
+// main24.cc is a part of the PYTHIA event generator.
+// Copyright (C) 2012 Peter Skands, Torbjorn Sjostrand.
+// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
+// Please respect the MCnet Guidelines, see GUIDELINES for details.
+
+// This is a simple test program. 
+// It illustrates how to run SUSY processes in Pythia8.
+// All input is specified in the main22.cmnd file.
+
+#include "Pythia.h"
+
+using namespace Pythia8; 
+
+int main() {
+
+  // Generator. Shorthand for the event.
+  Pythia pythia;
+  Event& event = pythia.event;
+
+  // Read in commands from external file.
+  pythia.readFile("main24.cmnd");    
+
+  // Extract settings to be used in the main program.
+  int nEvent   = pythia.mode("Main:numberOfEvents");
+  int nAbort   = pythia.mode("Main:timesAllowErrors"); 
+  double eCM   = pythia.parm("Beams:eCM");
+
+  // Initialize.
+  pythia.init();
+
+  // Histograms.
+  double epTol = 1e-6 * eCM;
+  Hist epCons("deviation from energy-momentum conservation",100,0.,epTol);
+  Hist nFinal("final particle multiplicity",100,-0.5,799.5);
+  Hist dnparticledy("dn/dy for particles",100,-10.,10.);
+
+  // Begin event loop.
+  int iAbort = 0;
+  for (int iEvent = 0; iEvent < nEvent; ++iEvent) {
+
+    // Generate events. Quit if failure.
+    if (!pythia.next()) {
+      if (++iAbort < nAbort) continue;
+      cout << " Event generation aborted prematurely, owing to error!\n"; 
+      break;
+    }
+
+    // Loop over final particles in the event. 
+    int nFin = 0;
+    Vec4 pSum;
+    for (int i = 0; i < event.size(); ++i) if (event[i].isFinal()) {
+      nFin++;
+      pSum += event[i].p();
+      dnparticledy.fill(event[i].y());
+    }
+
+    // Check and print event with too big energy-momentum deviation.
+    nFinal.fill(nFin);
+    double epDev = abs(pSum.e() - eCM) + abs(pSum.px()) + abs(pSum.py())
+      + abs(pSum.pz());
+    epCons.fill(epDev);
+    if (epDev > epTol) {
+      cout << " Warning! Event with epDev = " << scientific 
+           << setprecision(4) << epDev << " now listed:";
+      event.list();
+    }
+
+  // End of event loop.
+  }
+
+  // Final statistics and histogram output.
+  pythia.stat();
+  cout << epCons << nFinal << dnparticledy; 
+
+  return 0;
+}
+