anchor.diff:              area(i,j) = sum_area
            enddo
         enddo
  +
  +      write(6,'(A,E24.16)') 'area = ', area(1,1)
   
         end
   
  
positive.code: 
  c           # nv has unit length
              do m = 1,3
                 ytangents(i,j,m) = taup(m)
              enddo
              edge_lengths(i,j,2) = tlen
           enddo
  
negative.code:          ENDDO
        ENDDO
  
        DO j = 1-mbc,my+mbc+1
           DO i =  -mbc,mx+mbc+1
  c           # Now do y-faces
  