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1 // 1
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24 // *******************************************
25 //
26 // G4ClassicalRK4 implementation
27 //
28 // Created: J.Apostolakis, V.Grichine - 30.01.
29 // -------------------------------------------
30
31 #include "G4ClassicalRK4.hh"
32 #include "G4ThreeVector.hh"
33
34 //////////////////////////////////////////////
35 //
36 // Constructor sets the number of variables (d
37 //
38 G4ClassicalRK4::
39 G4ClassicalRK4(G4EquationOfMotion* EqRhs, G4in
40 : G4MagErrorStepper(EqRhs, numberOfVariables
41 {
42 unsigned int noVariables= std::max(numberOf
43
44 dydxm = new G4double[noVariables];
45 dydxt = new G4double[noVariables];
46 yt = new G4double[noVariables];
47 }
48
49 //////////////////////////////////////////////
50 //
51 // Destructor
52 //
53 G4ClassicalRK4::~G4ClassicalRK4()
54 {
55 delete [] dydxm;
56 delete [] dydxt;
57 delete [] yt;
58 }
59
60 //////////////////////////////////////////////
61 //
62 // Given values for the variables y[0,..,n-1]
63 // dydx[0,...,n-1] known at x, use the classic
64 // method to advance the solution over an inte
65 // incremented variables as yout[0,...,n-1], w
66 // array from y. The user supplies the routine
67 // which returns derivatives dydx at x. The so
68 // NRC p. 712-713 .
69 //
70 void
71 G4ClassicalRK4::DumbStepper( const G4double yI
72 const G4double dy
73 G4double h,
74 G4double yO
75 {
76 const G4int nvar = GetNumberOfVariables();
77 G4int i;
78 G4double hh = h*0.5, h6 = h/6.0;
79
80 // Initialise time to t0, needed when it is
81 // [ Note: Only for time dependent fi
82 // is it neccessary to inte
83 yt[7] = yIn[7];
84 yOut[7] = yIn[7];
85
86 for(i=0; i<nvar; ++i)
87 {
88 yt[i] = yIn[i] + hh*dydx[i] ;
89 }
90 RightHandSide(yt,dydxt) ;
91
92 for(i=0; i<nvar; ++i)
93 {
94 yt[i] = yIn[i] + hh*dydxt[i] ;
95 }
96 RightHandSide(yt,dydxm) ;
97
98 for(i=0; i<nvar; ++i)
99 {
100 yt[i] = yIn[i] + h*dydxm[i] ;
101 dydxm[i] += dydxt[i] ;
102 }
103 RightHandSide(yt,dydxt) ;
104
105 for(i=0; i<nvar; ++i) // Final RK4 output
106 {
107 yOut[i] = yIn[i]+h6*(dydx[i]+dydxt[i]+2.0*
108 }
109 if ( nvar == 12 ) { NormalisePolarizationVe
110
111 } // end of DumbStepper .....................
112
113 //////////////////////////////////////////////
114 //
115 // StepWithEst
116
117 void
118 G4ClassicalRK4::StepWithEst( const G4double*,
119 const G4double*,
120 G4double,
121 G4double*,
122 G4double&,
123 G4double&,
124 const G4double*,
125 G4double*
126 {
127 G4Exception("G4ClassicalRK4::StepWithEst()",
128 FatalException, "Method no longe
129
130 } // end of StepWithEst .....................
131