! source file: /Users/oschlies/UVIC/master/source/mom/hmixc.F
      subroutine hmixc (joff, js, je, is, ie)

!=======================================================================
!     set horizontal mixing coeffs on north and east face of "t" and
!     "u" cells.

!     input:
!       joff = offset relating "j" in the MW to latitude "jrow"
!       js   = starting row in the MW
!       je   = ending row in the MW
!       is   = starting longitude index in the MW
!       ie   = ending longitude index in the MW

!     based on code by: R. C. Pacanowski
!=======================================================================

      include "param.h"
      include "grdvar.h"
      include "hmixc.h"
      include "mw.h"
      include "scalar.h"
      include "switch.h"

!-----------------------------------------------------------------------
!     bail out if starting row exceeds ending row
!-----------------------------------------------------------------------

      if (js .gt. je) return

!-----------------------------------------------------------------------
!     set all horizontal mixing coefficients
!-----------------------------------------------------------------------

      jrowstart = js + joff
      jrowend   = min(je + joff + 2,jmt)

!     for momentum... set coefficients for all latitudes

      if (first) then
        visc_cnu  = am
        visc_ceu  = am
        do jrow=jrowstart,jrowend
          jm1 = max(1,jrow-1)
          jp1 = min(jmt,jrow+1)
          amc_north(jrow) = visc_cnu*cst(jp1)*dytr(jp1)
     &                              *csur(jrow)*dyur(jrow)
          amc_south(jrow) = visc_cnu*cst(jrow)*dytr(jrow)
     &                              *csur(jrow)*dyur(jrow)
        enddo
      endif

!     for tracers... set coefficients for all latitudes

      if (first) then
        diff_cnt  = ah
        diff_cet  = ah

        do jrow=jrowstart,jrowend
          jm1 = max(1,jrow-1)
          jp1 = min(jmt,jrow+1)
          ahc_north(jrow) = diff_cnt*csu(jrow)*dyur(jrow)*cstr(jrow)
     &                              *dytr(jrow)
          ahc_south(jrow) = diff_cnt*csu(jm1)*dyur(jm1)*cstr(jrow)
     &                              *dytr(jrow)
        enddo
      endif

      return
      end