// Author: Egon Pavlica <http://www.ses-ng.si/~pavlica/>

#include "LRandomWalk.h"
#include "nrutil.h"
#include "nr.h"
#include <time.h>
#include <stdlib.h>
#include <iostream>

//________________________________________
//  Simulation of random walk
//
// an exaple of simulation is in file 
// simple.cc
//
//
// Logs:
//
//  $Log: LRandomWalk.cc,v $
//  Revision 1.3  2003/06/26 11:24:25  cvs
//  modified particle moving with LMiki and faster LDisorder operations
//
//  Revision 1.2  2003/06/26 09:27:11  cvs
//  added log fields...
//

ClassImp(LRandomWalk)

int Smer(){
  //this is random direction selection with only three possible 
  //values (-1,0,1), which are all equivalently probable
  static long seed=-time(NULL);
  float rand=ran1(&seed);
  if (rand>0.66666) return 1;
  if (rand<0.33334) return -1;
  return 0;
}

 void LRandomWalk::RandomStep(){
  //particle do a random step 
  MoveTo(Smer(),Smer(),Smer());
  //if (fverbose) cout<<"Energy: "<<fspace[e->i][e->j][e->k]<<endl;
}

 void LRandomWalk::Init(){
  //get fe,fspace,fwspace and from LMiki class
  if (!fe) fe=GetParticle();
  if (!fspace) fspace=GetSpace();
}

 void LRandomWalk::Walk(){
  //do a random walk of the particle, correcting energies and
  //calculating time with uncertainty principle.
  float hplank=6e-34;
  float oldenergy,newe,delta;
  Init();
  if (fverbose) std::cout<<"Random Walk simulationn"; 
  while (fspace->IsInside(fe)) {
    oldenergy=fe->GetEnergy();  
    RandomStep();
    newe=fspace->GetEnergy(fe->i,fe->j,fe->k);
    fe->SetEnergy(newe);
    delta=fabs(oldenergy-newe);
    if (delta!=0.0)
      fe->time+=hplank/delta;
    if (fverbose) std::cout<<fe->i<<","<<fe->j<<","<<fe->k<<std::endl;
    if (fverbose) std::cout<<"Time: "<<fe->time<<"tEnergy: "<<newe<<std::endl;
  }
  if (fverbose) std::cout<<"Particle exited the space at "<<fe->i<<","<<fe->j<<","<<fe->k<<std::endl; 
}