Import Geant4 0.0.0 source tree

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+// This code implementation is the intellectual property of
+// the RD44 GEANT4 collaboration.
+//
+// By copying, distributing or modifying the Program (or any work
+// based on the Program) you indicate your acceptance of this statement,
+// and all its terms.
+//
+// $Id: G4ClassicalRK4.cc,v 2.8 1998/11/17 18:20:10 japost Exp $
+// GEANT4 tag $Name: geant4-00 $
+//
+#include "G4ClassicalRK4.hh"
+#include "G4ThreeVector.hh"
+
+
+//////////////////////////////////////////////////////////////////
+//
+// Constructor sets the number of variables (default = 6)
+
+G4ClassicalRK4:: G4ClassicalRK4(G4Mag_EqRhs *EqRhs, G4int numberOfVariables): 
+G4MagErrorStepper(EqRhs, numberOfVariables),
+  fNumberOfVariables(numberOfVariables)
+{
+   dydxm = new G4double[fNumberOfVariables];
+   dydxt = new G4double[fNumberOfVariables]; 
+   yt    = new G4double[fNumberOfVariables]; 
+}
+
+////////////////////////////////////////////////////////////////
+//
+// Destructor
+
+G4ClassicalRK4:: ~G4ClassicalRK4()
+{
+  delete[] dydxm;
+  delete[] dydxt;
+  delete[] yt;
+}
+
+//////////////////////////////////////////////////////////////////////
+//
+// Given values for the variables y[0,..,n-1] and their derivatives
+// dydx[0,...,n-1] known at x, use the classical 4th Runge-Kutta
+// method to advance the solution over an interval h and return the
+// incremented variables as yout[0,...,n-1], which not be a distinct
+// array from y. The user supplies the routine RightHandSide(x,y,dydx),
+// which returns derivatives dydx at x. The source is routine rk4 from
+// NRC p. 712-713 .
+
+void
+G4ClassicalRK4::DumbStepper( const G4double  yIn[],
+			     const G4double  dydx[],
+			     const G4double  h,
+			 	   G4double  yOut[])
+{
+  const G4int nvar = fNumberOfVariables;   //  GetNumberOfVariables(); 
+  G4int i;
+  G4double  hh = h*0.5 , h6 = h/6.0  ;
+
+
+  for(i=0;i<nvar;i++)
+  {
+    yt[i] = yIn[i] + hh*dydx[i] ;             // 1st Step K1=h*dydx
+  }
+  RightHandSide(yt,dydxt) ;                   // 2nd Step K2=h*dydxt
+
+  for(i=0;i<nvar;i++)
+  { 
+    yt[i] = yIn[i] + hh*dydxt[i] ;
+  }
+  RightHandSide(yt,dydxm) ;                   // 3rd Step K3=h*dydxm
+
+  for(i=0;i<nvar;i++)
+  {
+    yt[i]   = yIn[i] + h*dydxm[i] ;
+    dydxm[i] += dydxt[i] ;                    // now dydxm=(K2+K3)/h
+  }
+  RightHandSide(yt,dydxt) ;                   // 4th Step K4=h*dydxt
+ 
+  for(i=0;i<nvar;i++)    // Final RK4 output
+  {
+    yOut[i] = yIn[i] + h6*(dydx[i]+dydxt[i]+2.0*dydxm[i]); //+K1/6+K4/6+(K2+K3)/3
+  }
+  // NormaliseTangentVector( yOut );
+  
+  return ;
+
+}  // end of DumbStepper ....................................................
+
+////////////////////////////////////////////////////////////////////
+//
+//   
+
+void
+G4ClassicalRK4::StepWithEst( const G4double  yIn[],
+			     const G4double  dydx[],
+			     const G4double  h,
+			 	   G4double  yOut[],
+                                   G4double& alpha2,
+                                   G4double& beta2,
+			     const G4double  B1[],
+			           G4double  B2[]         ) 
+{
+
+ G4Exception(" G4ClassicalRK4::StepWithEst ERROR: this Method is no longer used.");
+
+#if 0  //  const G4int nvar = 6 ; 
+  const G4int nvar = GetNumberOfVariables(); 
+  G4int i;
+  G4double  hh = h*0.5 , h6 = h/6.0 ;
+  G4double B[3] ;
+  alpha2 = 0 ;
+  beta2 = 0 ;
+
+  for(i=0;i<nvar;i++)
+  {
+    yt[i] = yIn[i] + hh*dydx[i] ;             // 1st Step K1=h*dydx
+  }
+  GetEquationOfMotion()->EvaluateRhsReturnB(yt,dydxt,B) ;  //  Calculates yderive & 
+                                                      // returns B too!
+   //  RightHandSide(yt,dydxt) ;                   // 2nd Step K2=h*dydxt
+
+  for(i=0;i<nvar;i++)
+  { 
+    yt[i] = yIn[i] + hh*dydxt[i] ;
+  }
+   GetEquationOfMotion()->EvaluateRhsReturnB(yt,dydxm,B2) ;  
+  //  RightHandSide(yt,dydxm) ;                   // 3rd Step K3=h*dydxm
+
+  for(i=0;i<3;i++)
+  {
+     beta2 +=  dydx[i+3] *dydx[i+3] 
+	     + dydxt[i+3]*dydxt[i+3] 
+             + dydxm[i+3]*dydxm[i+3] ;
+     alpha2 += B1[i]*B1[i] + B[i]*B[i] + B2[i]*B2[i] ;
+  }
+  for(i=0;i<nvar;i++)
+  {
+    yt[i]   = yIn[i] + h*dydxm[i] ;
+    dydxm[i] += dydxt[i] ;                    // now dydxm=(K2+K3)/h
+  }
+   GetEquationOfMotion()->EvaluateRhsReturnB(yt,dydxt,B2) ;  
+  //  RightHandSide(yt,dydxt) ;                   // 4th Step K4=h*dydxt
+ 
+  for(i=0;i<nvar;i++)    // Final RK4 output
+  {
+    yOut[i] = yIn[i] + h6*(dydx[i]+dydxt[i]+2.0*dydxm[i]); //+K1/6+K4/6+(K2+K3)/3
+  }
+  for(i=0;i<3;i++)
+  { 
+     beta2 += dydxt[i+3]*dydxt[i+3] ;
+     alpha2 += B2[i]*B2[i] ;
+  }
+  beta2  *= 0.25*h*h;
+  alpha2 *= sqr(GetEquationOfMotion()->FCof()*h)*0.25 ;
+  // NormaliseTangentVector( yOut );
+
+#endif
+
+  return ;
+
+}  // end of StepWithEst ......................................................
+   
+
+