anchor.diff:  !f2py intent(in) :: a
   !f2py intent(out) :: lda
   
  -! call this as: lda = reconstruction_f.nolimit(1,a,qx,qy,ng)
  +! call this as: lda = reconstruction_f.limit2(1,a,qx,qy,ng)
   
     integer :: ilo, ihi, jlo, jhi
     integer :: nx, ny
  
positive.code:      do j = jlo-3, jhi+3
          do i = ilo-3, ihi+3
  
             test = (a(i+1,j) - a(i,j))*(a(i,j) - a(i-1,j))
  
             if (test > 0.0d0) then
  
negative.code:      do j = jlo-3, jhi+3
          do i = ilo-3, ihi+3
  
             ! test whether we are at an extremum
             test = (a(i,j+1) - a(i,j))*(a(i,j) - a(i,j-1))
  
             if (test > 0.0d0) then
  