anchor.diff:        integer rr2
         parameter(rr2 = 4)
         integer i2(0:rr2-1),j2(0:rr2-1)
  +
  +      integer a(2,2)
  +      integer ii,jj,iff,jff,dc(2),df(2,0:rr2-1)
  +      double precision shiftx(0:rr2-1), shifty(0:rr2-1)
  +      logical check_indices
   
         r2 = refratio*refratio
         if (r2 .ne. rr2) then
  
positive.code:       double precision qcoarse(1-mbc:mx+mbc,1-mbc:my+mbc,meqn)
  
        integer mq,r2, m
        integer i, ic1, ic2, ibc, ii, ifine
        integer j, jc1, jc2, jbc, jj, jfine
        integer ic_add, jc_add, ic, jc, mth
        double precision shiftx, shifty, gradx, grady, qc, sl, sr, value
        double precision compute_slopes
  
  c     # This should be refratio*refratio.
  
negative.code:       integer i2(0:rr2-1),j2(0:rr2-1)
        logical is_valid_interp
        logical skip_this_grid
  
        integer a(2,2)
        integer ii,jj,dc(2),df(2,0:rr2-1),iff,jff
        double precision shiftx(0:rr2-1),shifty(0:rr2-1)
  
        mth = 5
        r2 = refratio*refratio
  