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## Rivet analyses reference

### EXAMPLE_MINIMIZE

A demo of how to use the built-in function minimizer
Experiment: ()
Status: EXAMPLE
Authors:
• Andy Buckley
No references listed
Beams: * *
Beam energies: ANY
Run details:
• All event types will be accepted.

A brief demonstration of using the MendelMin minimizer to wrap a C++ function and minimize its value.

Source code: EXAMPLE_MINIMIZE.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Tools/MendelMin.hh" namespace Rivet { double f1(double p0, double p1) { const double x = p0 - 0.3; const double y = p1 - 0.5; return (x*x + 2*y*y) + 0.1*sin(x)*sin(y); } double f2(const MendelMin::Params& p, const MendelMin::Params&) { return f1(p[0], p[1]); } double f3(const MendelMin::Params& p) { return f1(p[0], p[1]); } /// @brief Demo of using the Rivet function minimizer class EXAMPLE_MINIMIZE : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(EXAMPLE_MINIMIZE); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run // void init() { } /// Perform the per-event analysis void analyze(const Event& event) { // MendelMin mm(f2, 2, {}); MendelMin mm(f3, 2); const double best = mm.evolve(20); valarray fittest = mm.fittest(); // cout << "FOUND ANSWER: " << f2(fittest, {}) << " == " << best << "; "; cout << "FOUND ANSWER: " << f3(fittest) << " == " << best << "; "; for (double x : fittest) cout << x << " "; cout << endl; valarray right{0.3, 0.5}; // cout << "RIGHT ANSWER: " << f2(right, {}) << "; "; cout << "RIGHT ANSWER: " << f3(right) << "; "; for (double x : right) cout << x << " "; cout << endl; } /// Normalise histograms etc., after the run // void finalize() { } //@} }; DECLARE_RIVET_PLUGIN(EXAMPLE_MINIMIZE); }