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source: svn/trunk/external/fastjet/tools/Subtractor.hh@ 1204

Last change on this file since 1204 was 999, checked in by Pavel Demin, 12 years ago

add fastjet/tools

File size: 3.7 KB
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1//STARTHEADER
2// $Id: Subtractor.hh 2577 2011-09-13 15:11:38Z salam $
3//
4// Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
5//
6//----------------------------------------------------------------------
7// This file is part of FastJet.
8//
9// FastJet is free software; you can redistribute it and/or modify
10// it under the terms of the GNU General Public License as published by
11// the Free Software Foundation; either version 2 of the License, or
12// (at your option) any later version.
13//
14// The algorithms that underlie FastJet have required considerable
15// development and are described in hep-ph/0512210. If you use
16// FastJet as part of work towards a scientific publication, please
17// include a citation to the FastJet paper.
18//
19// FastJet is distributed in the hope that it will be useful,
20// but WITHOUT ANY WARRANTY; without even the implied warranty of
21// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22// GNU General Public License for more details.
23//
24// You should have received a copy of the GNU General Public License
25// along with FastJet. If not, see <http://www.gnu.org/licenses/>.
26//----------------------------------------------------------------------
27//ENDHEADER
28
29#ifndef __FASTJET_TOOLS_SUBTRACTOR_HH__
30#define __FASTJET_TOOLS_SUBTRACTOR_HH__
31
32#include "fastjet/tools/Transformer.hh" // to derive Subtractor from Transformer
33#include "fastjet/tools/BackgroundEstimatorBase.hh" // used as a ctor argument
34
35FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
36
37
38//----------------------------------------------------------------------
39/// @ingroup tools_background
40/// \class Subtractor
41/// Class that helps perform jet background subtraction.
42///
43/// This class derives from Transformer and makes use of a pointer to
44/// a BackgroundEstimatorBase object in order to determine the background
45/// in the vicinity of a given jet and then subtract area*background from
46/// the jet. It can also be initialised with a specific fixed value for the
47/// background pt density.
48///
49/// \section input Input conditions
50///
51/// The original jet must have area support (4-vector)
52///
53/// \section output Output/interface
54///
55/// The underlying structure of the returned, subtracted jet
56/// (i.e. constituents, pieces, etc.) is identical to that of the
57/// original jet.
58///
59class Subtractor : public Transformer{
60public:
61 /// define a subtractor based on a BackgroundEstimator
62 Subtractor(BackgroundEstimatorBase * bge) :
63 _bge(bge), _rho(-1.0) {}
64
65 /// define a subtractor that uses a fixed value of rho, the background
66 /// pt density per unit area (which must be positive)
67 Subtractor(double rho);
68
69 /// default constructor
70 Subtractor() : _bge(0), _rho(_invalid_rho) {}
71
72 /// default dtor
73 virtual ~Subtractor(){};
74
75 /// returns a jet that's subtracted
76 ///
77 /// \param jet the jet that is to be subtracted
78 /// \return the subtracted jet
79 virtual PseudoJet result(const PseudoJet & jet) const;
80
81 /// class description
82 virtual std::string description() const;
83
84protected:
85
86 /// the tool used to estimate the background
87 /// if has to be mutable in case its underlying selector takes a reference jet
88 mutable BackgroundEstimatorBase * _bge;
89 /// the fixed value of rho to use if the user has selected that option
90 double _rho;
91
92 /// a value of rho that is used as a default to label that the stored
93 /// rho is not valid for subtraction.
94 //
95 // NB: there are two reasons for not having the value written here:
96 // 1) that it caused problems on karnak with g++ 4.0.1 and 2) that
97 // we anyway like -infinity as a default, and since that's a function,
98 // that's not allowed in an include file.
99 static const double _invalid_rho;
100};
101
102FASTJET_END_NAMESPACE
103
104#endif // __FASTJET_TOOLS_SUBTRACTOR_HH__
105
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