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G4PolynomialPDF.hh
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27 // -------------------------------------------------------------------
28 // GEANT4 Class file
29 //
30 //
31 // File name: G4PolynomialPDF
32 //
33 // Author: Jason Detwiler (jasondet@gmail.com)
34 //
35 // Creation date: Aug 2012
36 //
37 // Description: Evaluates, generates random numbers from, and evaluates
38 // the inverse of a polynomial PDF, its CDF, and its first and second
39 // derivative.
40 //
41 // -------------------------------------------------------------------
42 
43 #ifndef G4POLYNOMIALPDF_HH
44 #define G4POLYNOMIALPDF_HH
45 
46 #include "globals.hh"
47 #include <vector>
48 
50 {
51  public:
52  G4PolynomialPDF(size_t n = 0, const double* coeffs = nullptr,
53  G4double x1=0, G4double x2=1);
54 
56  // Setters and Getters for coefficients
57  inline void SetNCoefficients(size_t n) { fCoefficients.resize(n); fChanged = true; }
58  inline size_t GetNCoefficients() const { return fCoefficients.size(); }
59  inline void SetCoefficients(const std::vector<G4double>& v) {
60  fCoefficients = v; fChanged = true; Simplify();
61  }
62  inline G4double GetCoefficient(size_t i) const { return fCoefficients[i]; }
63  void SetCoefficient(size_t i, G4double value, bool doSimplify);
64  void SetCoefficients(size_t n, const G4double* coeffs);
65  void Simplify();
66 
67  // Set the domain over which random numbers are generated and over which
68  // the CDF is evaluated
69  void SetDomain(G4double x1, G4double x2);
70 
71  // Normalize PDF to 1 over domain fX1 to fX2. Used internally by
72  // GetRandomX(), but the user may want to call this as well for evaluation
73  // purposes.
74  void Normalize();
75 
76  // Evaluate (d/dx)^ddxPower f(x) (-1 <= ddxPower <= 2)
77  // ddxPower = -1 -> CDF;
78  // ddxPower = 0 -> PDF
79  // ddxPower = 1 -> PDF'
80  // ddxPower = 2 -> PDF''
81  G4double Evaluate(G4double x, G4int ddxPower = 0);
82 
83  // Generate a random number from this PDF
85 
86  // Set the tolerance to within negative minima are checked
87  inline void SetTolerance(G4double tolerance) { fTolerance = tolerance; }
88 
89  // Find a value x between x1 and x2 at which ddxPower[PDF](x) = p.
90  // ddxPower = -1 -> CDF;
91  // ddxPower = 0 -> PDF
92  // ddxPower = 1 -> PDF'
93  // (ddxPower = 2 not implemented)
94  // Solves analytically when possible, and otherwise uses the Newton-Raphson
95  // method to find the zero of ddxPower[PDF](x) - p.
96  // If not found in range, returns the nearest boundary.
97  // Beware that if x1 and x2 are not set carefully there may be multiple
98  // solutions, and care is not taken to select a particular one among them.
99  // Returns x2 on error
100  G4double GetX( G4double p, G4double x1, G4double x2, G4int ddxPower = 0,
101  G4double guess = 1.e99, G4bool bisect = true );
102  inline G4double EvalInverseCDF(G4double p) { return GetX(p, fX1, fX2, -1, fX1 + p*(fX2-fX1)); }
104 
105  void Dump();
106 
107  protected:
108  // Checks for negative values between x1 and x2. Used by GetRandomX()
110 
113  std::vector<G4double> fCoefficients;
117 };
118 
119 #endif
std::vector< G4double > fCoefficients
void SetCoefficients(const std::vector< G4double > &v)
G4double GetRandomX()
const char * p
Definition: xmltok.h:285
void SetTolerance(G4double tolerance)
void SetNCoefficients(size_t n)
G4PolynomialPDF(size_t n=0, const double *coeffs=nullptr, G4double x1=0, G4double x2=1)
tuple x
Definition: test.py:50
G4double GetX(G4double p, G4double x1, G4double x2, G4int ddxPower=0, G4double guess=1.e99, G4bool bisect=true)
int G4int
Definition: G4Types.hh:78
G4double Bisect(G4double p, G4double x1, G4double x2)
G4double GetCoefficient(size_t i) const
const XML_Char int const XML_Char * value
Definition: expat.h:331
void SetDomain(G4double x1, G4double x2)
bool G4bool
Definition: G4Types.hh:79
const G4int n
tuple v
Definition: test.py:18
G4bool HasNegativeMinimum(G4double x1, G4double x2)
size_t GetNCoefficients() const
G4double EvalInverseCDF(G4double p)
G4double Evaluate(G4double x, G4int ddxPower=0)
double G4double
Definition: G4Types.hh:76
void SetCoefficient(size_t i, G4double value, bool doSimplify)