1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/AnalysisHandler.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// Analysis of the generated cross-section
 9  class MC_XS : public Analysis {
10  public:
11
12    RIVET_DEFAULT_ANALYSIS_CTOR(MC_XS);
13
14
15    /// @name Analysis methods
16    /// @{
17
18    /// Book histograms and initialise projections before the run
19    void init() {
20      /// @todo Convert to Scatter1D or Counter
21      book(_h_XS, "XS");
22      book(_h_N, "N", 1, 0.0, 1.0);
23      book(_h_pmXS, "pmXS", 2, -1.0, 1.0);
24      book(_h_pmN, "pmN", 2, -1.0, 1.0);
25    }
26
27
28    /// Perform the per-event analysis
29    void analyze(const Event& event) {
30
31      const size_t numWeights = event.weights().size();
32      const vector<pair<double,double>> xsecs = event.crossSections();
33      for (size_t m = 0; m < numWeights; ++m) {
34        size_t idx = (xsecs.size() == numWeights)? m : 0;
35        const double xs    = xsecs[idx].first;
36        const double xserr = xsecs[idx].second;
37        _h_XS.get()->persistent(m)->set(xs, xserr);
38        const double weight = event.weights()[m];
39        _h_pmXS.get()->persistent(m)->fill(0.5*(weight > 0 ? 1. : -1), abs(weight));
40        _h_pmN.get()->persistent(m)->fill(0.5*(weight > 0 ? 1. : -1), 1.);
41        _h_N.get()->persistent(m)->fill(0.5, 1.0);
42      }
43
44    }
45
46
47    /// Normalise histograms etc., after the run
48    void finalize() {
49      scale(_h_pmXS, crossSection()/picobarn/sumOfWeights());
50    }
51
52    /// @}
53
54
55    /// @name Histograms
56    /// @{
57    Estimate0DPtr _h_XS;
58    Histo1DPtr _h_pmXS, _h_pmN, _h_N;
59    /// @}
60
61  };
62
63
64
65  RIVET_DECLARE_PLUGIN(MC_XS);
66
67}