/***************************************************************************
                 module classe ztuv_lfil.h  -  description
***************************************************************************/
// Mohamed Berrada
// locean-ipsl.upmc, Paris, July 20, 2011
//===========================================================================
//                          methode forward
forward (YREAL x1,YREAL x2,YREAL x3)
{ /*	1	from	dta_lfil		1  i+1 	j    k     t-1
	2	from	dta_lfil		1  i 	j    k     t-1 
	3	from	dta_lfil		1  i 	j+1  k     t-1 */
  if(Yt==1){
    YS1=0;
    YS2=0;
  }
  else{
    if(Yi==0 || Yi==NX-1 || Yj==0 || Yj==NY-1 || Yk==NZ-1){
      YS1=0.;
      YS2=0;
    }
    else{
      double zabe1 = fsaht_fil * umask(Yi,Yj,Yk) * ze1ur(Yi,Yj);
      double zabe2 = fsaht_fil * vmask(Yi,Yj,Yk) * ze2vr(Yi,Yj);
      YS1=   zabe1 * ( x1 - x2);
      YS2=   zabe2 * ( x3 - x2);
    }
  }
  //
}

//===========================================================================
//                         methode  backward

backward (YREAL x1,YREAL x2,YREAL x3)
{
  YJ1I1=0.;     YJ1I2=0.;    YJ1I3=0.;   
  YJ2I1=0.;     YJ2I2=0.;    YJ2I3=0.;  
  
  if(Yt==1){
    YJ1I1=0.;     YJ1I2=0.;    YJ1I3=0.;   
    YJ2I1=0.;     YJ2I2=0.;    YJ2I3=0.;  
  }
  else{
    if(Yi==0 || Yi==NX-1 || Yj==0 || Yj==NY-1 || Yk==NZ-1){
      YJ1I1=0.;     YJ1I2=0.;    YJ1I3=0.;   
      YJ2I1=0.;     YJ2I2=0.;    YJ2I3=0.;  
    }
    else{
      double zabe1 = fsaht_fil * umask(Yi,Yj,Yk) * ze1ur(Yi,Yj);
      double zabe2 = fsaht_fil * vmask(Yi,Yj,Yk) * ze2vr(Yi,Yj);
      YJ1I1=zabe1;     YJ1I2=-zabe1;    YJ1I3=0.;   
      YJ2I1=0.;     YJ2I2=-zabe2;    YJ2I3=zabe2;  
    }
  }
  //

}