KVRungeKutta.h

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#ifndef __KVRUNGEKUTTA_H
#define __KVRUNGEKUTTA_H
 
#include "KVBase.h"
 
#define SAFETY 0.9
#define PGROW -0.2
#define PSHRNK -0.25
#define ERRCON 1.89e-4
#define MAXSTP 10000
#define TINY 1.0e-30
 
/*The value ERRCON equals (5/SAFETY) raised to the power (1/PGROW), see use below.*/
 
class KVRungeKutta : public KVBase {
   static Double_t a2, a3, a4, a5, a6, b21;
   static Double_t b31, b32, b41, b42, b43;
   static Double_t b51, b52, b53, b54;
   static Double_t b61, b62, b63;
   static Double_t b64, b65, c1 ;
   static Double_t c3, c4, c6;
   static Double_t dc5;
protected:
    Int_t nvar;
    Double_t eps;
    Double_t hmin;
    Int_t nok;
    Int_t nbad;
 
   Double_t* y, *yscal, *dydx, *yerr, *ytemp, *yout;
   Double_t x, hnext, hdid;
   Double_t* ak2, *ak3, *ak4, *ak5, *ak6;
   Double_t dc1, dc3, dc4, dc6;
   Bool_t fOK;
   Bool_t fInitialDeriv;
   virtual void rkqs(Double_t htry);
   virtual void rkck(Double_t h);
 
public:
   KVRungeKutta() {};
   KVRungeKutta(Int_t N, Double_t PREC = 1.e-8, Double_t MINSTEP = 0.0);
   virtual ~KVRungeKutta();
 
   virtual void Integrate(Double_t* ystart, Double_t x1, Double_t x2, Double_t h1);
 
   virtual void CalcDerivs(Double_t X, Double_t* Y, Double_t* DYDX) = 0;
 
   Int_t GetNGoodSteps() const
   {
      return nok;
   }
   Int_t GetNBadSteps() const
   {
      return nbad;
   }
   Bool_t IsOK() const
   {
      return fOK;
   }
 
   ClassDef(KVRungeKutta, 0) //Adaptive step-size 4th order Runge-Kutta ODE integrator from Numerical Recipes
};
 
#endif