Geant4_10
G4LogLogInterpolation.cc
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27 // $Id: G4LogLogInterpolation.cc 66241 2012-12-13 18:34:42Z gunter $
28 //
29 // Author: Maria Grazia Pia (Maria.Grazia.Pia@cern.ch)
30 // Sebastian Incerti (incerti@cenbg.in2p3.fr)
31 // Nicolas A. Karakatsanis (knicolas@mail.ntua.gr)
32 // History:
33 // -----------
34 // 31 Jul 2001 MGP Created
35 // 27 Jun 2008 SI Add check to avoid FPE errors
36 // 08 Dec 2008 NAK Log-Log interpolation math formula streamlined, self-test function
37 // 14 Jun 2008 NAK New implementation for log-log interpolation after directly loading
38 // logarithmic values from G4EMLOW dataset
39 // -------------------------------------------------------------------
40 
41 #include "G4LogLogInterpolation.hh"
42 
43 // Constructor
44 
46 { }
47 
48 // Destructor
49 
51 { }
52 
54 { return new G4LogLogInterpolation; }
55 
56 
58  const G4DataVector& points,
59  const G4DataVector& data) const
60 {
61  //G4cout << "G4LogLogInterpolation is performed (2 arguments) " << G4endl;
62  G4int nBins = data.size() - 1;
63 //G4double oldresult = 0.;
64  G4double value = 0.;
65  if (x < points[0])
66  {
67  value = 0.;
68  }
69  else if (bin < nBins)
70  {
71  G4double e1 = points[bin];
72  G4double e2 = points[bin+1];
73  G4double d1 = data[bin];
74  G4double d2 = data[bin+1];
75 // Check of e1, e2, d1 and d2 values to avoid floating-point errors when estimating the interpolated value below -- S.I., Jun. 2008
76  if ((d1 > 0.) && (d2 > 0.) && (e1 > 0.) && (e2 > 0.))
77  {
78 // Streamline the Log-Log Interpolation formula in order to reduce the required number of log10() function calls
79 // Variable oldresult contains the result of old implementation of Log-Log interpolation -- M.G.P. Jun. 2001
80 // oldresult = (std::log10(d1)*std::log10(e2/x) + std::log10(d2)*std::log10(x/e1)) / std::log10(e2/e1);
81 // oldresult = std::pow(10.,oldresult);
82 // Variable value contains the result of new implementation, after streamlining the math operation -- N.A.K. Oct. 2008
83  value = std::log10(d1)+(std::log10(d2/d1)/std::log10(e2/e1)*std::log10(x/e1));
84  value = std::pow(10.,value);
85 // Test of the new implementation result (value variable) against the old one (oldresult) -- N.A.K. Dec. 2008
86 // G4double diffResult = value - oldresult;
87 // G4double relativeDiff = 1e-11;
88 // Comparison of the two values based on a max allowable relative difference
89 // if ( std::fabs(diffResult) > relativeDiff*std::fabs(oldresult) )
90 // {
91 // Abort comparison when at least one of two results is infinite
92 // if ((!std::isinf(oldresult)) && (!std::isinf(value)))
93 // {
94 // G4cout << "G4LogLogInterpolation> Old Interpolated Value is:" << oldresult << G4endl;
95 // G4cout << "G4LogLogInterpolation> New Interpolated Value is:" << value << G4endl << G4endl;
96 // G4cerr << "G4LogLogInterpolation> Error in Interpolation:" << G4endl;
97 // G4cerr << "The difference between new and old interpolated value is:" << diffResult << G4endl << G4endl;
98 // }
99 // }
100  }
101  else value = 0.;
102  }
103  else
104  {
105  value = data[nBins];
106  }
107  return value;
108 }
109 
110 
111 // Nicolas A. Karakatsanis: New implementation of log-log interpolation after directly loading
112 // logarithmic values from G4EMLOW dataset
113 
115  const G4DataVector& points,
116  const G4DataVector& data,
117  const G4DataVector& log_points,
118  const G4DataVector& log_data) const
119 {
120  //G4cout << "G4LogLogInterpolation is performed (4 arguments) " << G4endl;
121  G4int nBins = data.size() - 1;
122  G4double value = 0.;
123  G4double log_x = std::log10(x);
124  if (x < points[0])
125  {
126  value = 0.;
127  }
128  else if (bin < nBins)
129  {
130  G4double log_e1 = log_points[bin];
131  G4double log_e2 = log_points[bin+1];
132  G4double log_d1 = log_data[bin];
133  G4double log_d2 = log_data[bin+1];
134 
135  //G4cout << "x = " << x << " , logx = " << log_x << " , bin = " << bin << G4endl;
136  //G4cout << "e1 = " << points[bin] << " d1 = " << data[bin] << G4endl;
137  //G4cout << "e2 = " << points[bin+1] << " d2 = " << data[bin+1] << G4endl;
138  //G4cout << "loge1 = " << log_e1 << " logd1 = " << log_d1 << G4endl;
139  //G4cout << "loge2 = " << log_e2 << " logd2 = " << log_d2 << G4endl;
140 
141 // Values e1, e2, d1 and d2 are the log values of the corresponding
142 // original energy and data values. Simple linear interpolation performed
143 // on loagarithmic data should be equivalent to log-log interpolation
144  value = log_d1 + (log_d2 - log_d1)*(log_x - log_e1)/(log_e2 - log_e1);
145 
146 // Delogarithmize to obtain interpolated value
147  value = std::pow(10.,value);
148  }
149  else
150  {
151  value = data[nBins];
152  }
153  return value;
154 }
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