anchor.diff:  subroutine calc_eta_star(ub, vb, eta, etastar, freesurfFac, nx, ny, dx, dy, dt)
     implicit none
   
  -  integer nx, ny, layers
  -  integer i, j, k
  +  integer nx, ny
  +  integer i, j
     double precision eta(0:nx+1, 0:ny+1)
     double precision etastar(0:nx+1, 0:ny+1)
     double precision ub(0:nx+1, 0:ny+1)
  
positive.code: 
    ! Grid
    double precision :: dx, dy
    double precision :: x_u(0:nx), y_u(0:ny)
    double precision :: x_v(0:nx), y_v(0:ny)
    double precision :: wetmask(0:nx+1, 0:ny+1)
    double precision :: hfacW(0:nx+1, 0:ny+1)
    double precision :: hfacE(0:nx+1, 0:ny+1)
  
negative.code: 
    integer nx, ny, layers
    integer i, j, k
    double precision u(0:nx+1, 0:ny+1, layers)
    double precision v(0:nx+1, 0:ny+1, layers)
    double precision zeta(0:nx+1, 0:ny+1, layers)
  