#include <TMath.h>

Double_t Novosibirsk(Double_t * x, Double_t * par)
{
  Double_t qa=0,qb=0,qc=0,qx=0,qy=0;
  
  Double_t peak = par[1];
  Double_t width = par[2];
  static const Double_t sln4 = TMath::Sqrt(TMath::Log(4));
  Double_t y = par[3]*sln4;
  Double_t tail = -TMath::Log(y + TMath::Sqrt(1 + y*y))/sln4;
  
  if(TMath::Abs(tail) < 1.e-7)
    {
      qc = 0.5*TMath::Power(((x[0]-peak)/width),2);
    }
  else 
    {
      qa = tail*sln4;
      qb = sinh(qa)/qa;
      qx = (x[0]-peak)/width*qb;
      qy = 1.+tail*qx;
      
      if( qy > 1.E-7)
	{
	  qc = 0.5*(TMath::Power((TMath::Log(qy)/tail),2) + tail*tail);
	}
      else
	{
	  qc = 15.0;
	}
    }
  return par[0]*TMath::Exp(-qc);
}

// TF1:
// TF1 f_novo("f_novo",Novosibirsk,0,10,4);