double GetPotentialValue(int& ix, int& iy);
double GetPotentialHVValue(int& ix, int& iy);

double induced (int istrip, double x, double y)
{
// x and y are the coorlocation of charge (e or hole)
// induced chardege on the strip "istrip" situated at the height y = d
// the center of the strip (istrip=0) is x = 0.
   
   double d=0.0285, strip_width=0.0080, xmax = 0.04, pi = 3.141592 ;
   double P, xc, dx, deltax = 0.002, deltay = 0.0005, fx, fy;
   int ix, iy;
   if ( y < 0. || y > d) return 0;
   xc = strip_width * istrip;
   dx = fabs( x-xc );
   if ( dx >= xmax ) return 0.;
   ix = int( dx / deltax );
   iy = int( y / deltay );
   fx = (dx - ix*deltax) / deltax;
   fy = (y - iy*deltay) / deltay;
   P = GetPotentialValue(ix,iy)    *(1.-fx)*(1.-fy) 
     + GetPotentialValue(ix+1,iy)  *fx*(1.-fy)
     + GetPotentialValue(ix,iy+1)  *(1.-fx)*fy 
     + GetPotentialValue(ix+1,iy+1)*fx*fy ;
//   cout <<"x,y,iy="<<x<<" "<<y<<" "<<iy<<" istrip,xc,dx,ix="
//   <<istrip<<" "<<xc<<" " <<dx<<" "<<ix<<" fx,fy="<<fx
//   <<" " <<fy<< ", P="<<P<<endl;
   return P;
}

double inducedHV (int istrip, double x, double y)
{
// induced charge fraction in the HV plane
// x and y are the coorlocation of charge (e or hole)
// induced chardege on the strip "istrip" situated at the height y = d
// the center of the strip (istrip=0) is x = 0.
   double d=0.0285, strip_width=0.0080, xmax = 0.04, pi = 3.141592 ;
   double PHV, xc, dx, deltax = 0.002, deltay = 0.0005, fx, fy;
   int ix, iy;
   if ( y < 0 || y > d) return 0;
   xc = strip_width * istrip;
   dx = fabs( x-xc );
   
   if ( dx > xmax ) return 0.;
   
   ix = int( dx / deltax );
   
   iy = int( y / deltay );
   
   fx = (x - ix*deltax) / deltax;
   fy = (y - iy*deltay) / deltay;
   PHV = GetPotentialHVValue(ix,iy)    *(1.-fx)*(1.-fy) 
       + GetPotentialHVValue(ix+1,iy)  *fx*(1.-fy)
       + GetPotentialHVValue(ix,iy+1)  *(1.-fx)*fy 
       + GetPotentialHVValue(ix+1,iy+1)*fx*fy ;
   return PHV;
}