anchor.diff:  ! -----------------------------------------------------------------------------
   
   subroutine evaluate_b_RedGrav(b,h,u,v,nx,ny,layers,gr)
  +  implicit none
  +
     ! Evaluate Bernoulli Potential at centre of grid box
     integer nx,ny,layers
  -  integer i,j,k
  +  integer i,j,k,l,m
     double precision h(0:nx+1,0:ny+1,layers)
     double precision u(0:nx+1,0:ny+1,layers)
     double precision v(0:nx+1,0:ny+1,layers)
  
positive.code: ! -----------------------------------------------------------------------------
  
  subroutine read_input_fileV(name,array,default,nx,ny,layers)
  
    implicit none
    character(30) name
    integer nx, ny, layers
    double precision array(0:nx+1,0:ny+1,layers), default
  
negative.code: subroutine evaluate_dvdt(dvdt, h,u,v,b,zeta,wind_y,fv, &
      au,ar,slip,dx,dy,hfacW,hfacE,nx,ny,layers,rho0, &
      spongeTimeScale,spongeV,RedGrav,botDrag)
    implicit none
  
    ! dvdt(i,j) is evaluated at the centre of the bottom edge of the
    ! grid box, the same place as v(i,j)
    integer nx,ny,layers
  