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TSpline2.cxx
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1// @(#)root/tmva $Id$
2// Author: Andreas Hoecker, Joerg Stelzer, Helge Voss
3
4/**********************************************************************************
5 * Project: TMVA - a Root-integrated toolkit for multivariate data analysis *
6 * Package: TMVA *
7 * Class : TSpline2 *
8 * Web : http://tmva.sourceforge.net *
9 * *
10 * Description: *
11 * Implementation (see header for description) *
12 * *
13 * Authors (alphabetical): *
14 * Andreas Hoecker <Andreas.Hocker@cern.ch> - CERN, Switzerland *
15 * Helge Voss <Helge.Voss@cern.ch> - MPI-K Heidelberg, Germany *
16 * Kai Voss <Kai.Voss@cern.ch> - U. of Victoria, Canada *
17 * *
18 * Copyright (c) 2005: *
19 * CERN, Switzerland *
20 * U. of Victoria, Canada *
21 * MPI-K Heidelberg, Germany *
22 * *
23 * Redistribution and use in source and binary forms, with or without *
24 * modification, are permitted according to the terms listed in LICENSE *
25 * (http://tmva.sourceforge.net/LICENSE) *
26 **********************************************************************************/
27
28/*! \class TMVA::TSpline2
29\ingroup TMVA
30Quadratic interpolation of TGraph
31*/
32
33#include "TMVA/TSpline2.h"
34
35#include "TGraph.h"
36#include "TMath.h"
37#include "TSpline.h"
38
40
41////////////////////////////////////////////////////////////////////////////////
42/// constructor from TGraph
43/// TSpline is a TNamed object
44
45TMVA::TSpline2::TSpline2( const TString& title, TGraph* theGraph )
46: fGraph( theGraph ) // not owned by TSpline2
47{
48 SetNameTitle( title, title );
49}
50
51////////////////////////////////////////////////////////////////////////////////
52/// destructor
53
55{
56 if (fGraph) delete fGraph; // ROOT's spline classes also own the TGraph
57}
58
59////////////////////////////////////////////////////////////////////////////////
60/// returns quadratically interpolated TGraph entry around x
61
63{
64 Double_t retval=0;
65
66 Int_t ibin = TMath::BinarySearch( fGraph->GetN(),
67 fGraph->GetX(),
68 x );
69
70 // sanity checks
71 if (ibin < 0 ) ibin = 0;
72 if (ibin >= fGraph->GetN()) ibin = fGraph->GetN() - 1;
73
74 Float_t dx = 0; // should be zero
75
76 if (ibin == 0 ) {
77
78 retval = Quadrax( x,
79 fGraph->GetX()[ibin] + dx,
80 fGraph->GetX()[ibin+1] + dx,
81 fGraph->GetX()[ibin+2] + dx,
82 fGraph->GetY()[ibin],
83 fGraph->GetY()[ibin+1],
84 fGraph->GetY()[ibin+2]);
85
86 }
87 else if (ibin >= (fGraph->GetN()-2)) {
88 ibin = fGraph->GetN() - 1; // always fixed to last bin
89
90 retval = Quadrax( x,
91 fGraph->GetX()[ibin-2] + dx,
92 fGraph->GetX()[ibin-1] + dx,
93 fGraph->GetX()[ibin] + dx,
94 fGraph->GetY()[ibin-2],
95 fGraph->GetY()[ibin-1],
96 fGraph->GetY()[ibin]);
97 }
98 else {
99
100 retval = ( Quadrax( x,
101 fGraph->GetX()[ibin-1] + dx,
102 fGraph->GetX()[ibin] + dx,
103 fGraph->GetX()[ibin+1] + dx,
104 fGraph->GetY()[ibin-1],
105 fGraph->GetY()[ibin],
106 fGraph->GetY()[ibin+1])
107 +
108 Quadrax( x, fGraph->GetX()[ibin] + dx,
109 fGraph->GetX()[ibin+1] + dx,
110 fGraph->GetX()[ibin+2] + dx,
111 fGraph->GetY()[ibin],
112 fGraph->GetY()[ibin+1],
113 fGraph->GetY()[ibin+2]) )*0.5;
114 }
115
116 return retval;
117}
118
119////////////////////////////////////////////////////////////////////////////////
120/// no coefficients to precompute
121
123{
124}
125
126////////////////////////////////////////////////////////////////////////////////
127/// no knots
128
129void TMVA::TSpline2::GetKnot( Int_t /*i*/, Double_t& /*x*/, Double_t& /*y*/ ) const
130{
131}
132
133////////////////////////////////////////////////////////////////////////////////
134/// quadratic interpolation
135/// Revised and checked by Francois Nov, 16th, 2000
136/// Note the beautiful non-spontaneous symmetry breaking ...
137/// It was checked that the old routine gave exactly the same answers.
138///
139
140Double_t TMVA::TSpline2::Quadrax( const Float_t dm,const Float_t dm1,const Float_t dm2,const Float_t dm3,
141 const Float_t cos1, const Float_t cos2, const Float_t cos3 ) const
142{
143 Float_t a = cos1*(dm2-dm3) + cos2*(dm3-dm1) + cos3*(dm1-dm2);
144 Float_t b = cos1*(dm2*dm2-dm3*dm3) + cos2*(dm3*dm3-dm1*dm1) + cos3*(dm1*dm1-dm2*dm2);
145 Float_t c = cos1*(dm2-dm3)*dm2*dm3 + cos2*(dm3-dm1)*dm3*dm1 + cos3*(dm1-dm2)*dm1*dm2;
146
147 Float_t denom = (dm2-dm3)*(dm3-dm1)*(dm1-dm2);
148
149 return (denom != 0.0) ? (-a*dm*dm+b*dm-c)/denom : 0.0;
150}
151
152
#define b(i)
Definition: RSha256.hxx:100
#define c(i)
Definition: RSha256.hxx:101
int Int_t
Definition: RtypesCore.h:45
double Double_t
Definition: RtypesCore.h:59
float Float_t
Definition: RtypesCore.h:57
#define ClassImp(name)
Definition: Rtypes.h:364
A TGraph is an object made of two arrays X and Y with npoints each.
Definition: TGraph.h:41
Quadratic interpolation of TGraph.
Definition: TSpline2.h:43
TSpline2(const TString &title, TGraph *theGraph)
constructor from TGraph TSpline is a TNamed object
Definition: TSpline2.cxx:45
virtual void BuildCoeff(void)
no coefficients to precompute
Definition: TSpline2.cxx:122
virtual ~TSpline2(void)
destructor
Definition: TSpline2.cxx:54
virtual Double_t Eval(Double_t x) const
returns quadratically interpolated TGraph entry around x
Definition: TSpline2.cxx:62
virtual void GetKnot(Int_t i, Double_t &x, Double_t &y) const
no knots
Definition: TSpline2.cxx:129
Double_t Quadrax(Float_t dm, Float_t dm1, Float_t dm2, Float_t dm3, Float_t cos1, Float_t cos2, Float_t cos3) const
quadratic interpolation Revised and checked by Francois Nov, 16th, 2000 Note the beautiful non-sponta...
Definition: TSpline2.cxx:140
virtual void SetNameTitle(const char *name, const char *title)
Set all the TNamed parameters (name and title).
Definition: TNamed.cxx:154
Basic string class.
Definition: TString.h:136
Double_t x[n]
Definition: legend1.C:17
Long64_t BinarySearch(Long64_t n, const T *array, T value)
Definition: TMathBase.h:274
auto * a
Definition: textangle.C:12