//-----------------------------------------------------------
// File and Version Information:
// $Id$
//
// Description:
//      Implementation of class PndEmcCR2RCPulseshape
//      see PndEmcCR2RCPulseshape.h for details
//
//-----------------------------------------------------------


// This Class' Header ------------------
#include "PndEmcCR2RCPulseshape.h"

// C/C++ Headers ----------------------
#include "assert.h"
#include "math.h"

// Collaborating Class Headers --------


// Class Member definitions -----------

PndEmcCR2RCPulseshape::PndEmcCR2RCPulseshape(double Tint, double Tdif, double Tsig) 
  : _Tint(Tint), _Tdif(Tdif), _Tsig(Tsig)    
{
  assert(_Tint!=_Tsig && _Tdif!=_Tsig);
}

double 
PndEmcCR2RCPulseshape::operator() (const double t, 
	    const double amp, const double toffset) const {
  if(_Tint==_Tdif)return degenerate_solution(t,amp,toffset);
  return general_solution(t,amp,toffset);
}


double 
PndEmcCR2RCPulseshape::general_solution(const double t, 
				    const double amp, 
				    const double toffset) const 
{
	double dt=t-toffset;
	if(dt<0) return 0;                           // piecewise definition!
	
	double l_int=1.0/_Tint;
	double l_dif=1.0/_Tdif;
	double l_sig=1.0/_Tsig;

	double term1=exp(-dt*l_int)*(l_sig-l_dif)*(dt-1/(l_sig-l_int)-1/(l_dif-l_int));
	double term2=exp(-dt*l_dif)*(l_sig-l_int)/(l_dif-l_int);
	double term3=exp(-dt*l_sig)*(l_dif-l_int)/(l_sig-l_int);
	
	return amp/((l_sig-l_dif)*(l_sig-l_int)*(l_dif-l_int))*(term1+term2-term3);
}


double 
PndEmcCR2RCPulseshape::degenerate_solution(const double t,  // for Tdif=Tint
				       const double amp, 
				       const double toffset) const 
{
	double dt=t-toffset;
	if(dt<0) return 0;                           // piecewise definition!
	
	double l_shaper=1.0/_Tdif;
	double l_sig=1.0/_Tsig;

	double dl=l_sig-l_shaper;

   double term1 = (exp(-l_shaper*dt)*(dl*dl*dt*dt/2.0 - dl*dt + 1.0 ) - 
         exp(-l_sig*dt));

	return amp*term1;
}

ClassImp(PndEmcCR2RCPulseshape)