anchor.diff:              end do
            end do
         end do
  -c     
   c     
         return
         end
  
positive.code:          endif
  c     
  c     
  c     # Store the value of j along this slice in the common block
  c     # comxyt in case it is needed in the Riemann solver (for
  c     # variable coefficient problems)
           jcom = j
  c     
  c     # compute modifications fadd and gadd to fluxes along this slice:
           ixy = 1
           call flux2(1,maxm,meqn,maux,mbc,mx,
       &        q1d,dtdx1d,aux1,aux2,aux3,
  
negative.code: c     
        do  i = 2-mbc, mx+mbc-1
  c     
  c        # copy data along a slice into 1d arrays:
           do m=1,meqn
              do j = 1-mbc, my+mbc
                 q1d(j,m) = qold(i,j,m)
  