************************************************************************
*     Randall R. Correll
*     Mijan F. Huq
*     Scott A. Klasky
*     Richard A. Matzner
*
*     COPYRIGHT 1995-1996

*  Applies new inout mask from apparent horizon solver to the 
*  grid functions--zeroes interior and extrapolate new values
*  for points emerging from the horizon.
************************************************************************
      subroutine remask(nx,ny,nz,g11,g12,g13,g22,g23,g33,
     &           k11,k12,k13,k21,k22,k23,k31,k32,k33,
     &           inout,inoutold)

      implicit none

      integer   nx,ny,nz
c     metric:   g_ij
      real*8    g11(nx,ny,nz), g12(nx,ny,nz), g13(nx,ny,nz),
     &                         g22(nx,ny,nz), g23(nx,ny,nz),
     &                                        g33(nx,ny,nz)
c     extrinsic curvature:   k^i_j
      real*8    k11(nx,ny,nz), k12(nx,ny,nz), k13(nx,ny,nz),
     &          k21(nx,ny,nz), k22(nx,ny,nz), k23(nx,ny,nz),
     &          k31(nx,ny,nz), k32(nx,ny,nz), k33(nx,ny,nz)
      real*8   inout(nx,ny,nz), inoutold(nx,ny,nz)

c     local variables
      integer   i, j, k

c     zero interior

      do k = 1, nz
      do j = 1, ny
      do i = 1, nx

         if ( inout(i,j,k) .eq. 0.0d0 ) then
            g11(i,j,k) = 0.0d0
            g12(i,j,k) = 0.0d0
            g13(i,j,k) = 0.0d0
            g22(i,j,k) = 0.0d0
            g23(i,j,k) = 0.0d0
            g33(i,j,k) = 0.0d0
            k11(i,j,k) = 0.0d0
            k12(i,j,k) = 0.0d0
            k13(i,j,k) = 0.0d0
            k21(i,j,k) = 0.0d0
            k22(i,j,k) = 0.0d0
            k23(i,j,k) = 0.0d0
            k31(i,j,k) = 0.0d0
            k32(i,j,k) = 0.0d0
            k33(i,j,k) = 0.0d0
         end if

       if (inout(i,j,k).eq.1.0d0 .and. inoutold(i,j,k).eq.0.0d0) then
c           call extrapolator
         end if

      end do
      end do
      end do

      return
      end