anchor.diff:          read(10) array
           close(10) 
           ! wrap array around for periodicity
  -        array(0,:,) = array(nx,:,)
  -        array(nx+1,:,) = array(1,:,)
  -        array(:,0,) = array(:,ny,)
  -        array(:,ny+1,) = array(:,1,)
  +        array(0,:) = array(nx,:)
  +        array(nx+1,:) = array(1,:)
  +        array(:,0) = array(:,ny)
  +        array(:,ny+1) = array(:,1)
       else
           array = default
       endif
  
positive.code:     integer nx,ny, i,j, maxits, n
      double precision dt
      double precision rjac, eps
      double precision rhs(nx,ny), 
      double precision res(nx,ny)
      double precision norm, norm0, norm_old
      double precision relax_param
  
negative.code:     integer nx,ny
  
      ! wrap array around for periodicity
      array(0,:) = array(nx,:)
      array(nx+1,:) = array(1,:)
      array(:,0) = array(:,ny)
      array(:,ny+1) = array(:,1)
  
      return
      end
  