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git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinder/trunk@3 89daf98e-ef62-4674-b946-b8ff9de2216c

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diff --git a/src/AHFinder_mask.F b/src/AHFinder_mask.F
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+c/*@@
+c  @file      AHFinder_mask.F
+c  @date      November 1998
+c  @author    Miguel Alcubierre
+c  @desc 
+c             Set up horizon mask for black hole excision.
+c  @enddesc 
+c@@*/
+
+c Note that including cactus.h will also include AHFinder.h
+!#include "cactus.h"
+#include "cctk.h"
+#include "cctk_parameters.h"
+#include "cctk_arguments.h"
+
+      subroutine AHFinder_mask(CCTK_FARGUMENTS)
+
+!     Set up the horizon mask.  All this routine does is
+!     set up the value of the grid function `ahmask' to
+!     one for points outside the horizon, and to zero
+!     for points inside the horizon.  This is only necessary
+!     if we want to use black hole excision.
+
+      use AHFinder_dat
+
+      implicit none
+
+      DECLARE_CCTK_FARGUMENTS
+      DECLARE_CCTK_PARAMETERS
+
+      integer i,j,k
+
+      CCTK_REAL zero,one
+      CCTK_REAL shrink
+
+
+!     *****************************
+!     ***   DEFINE {zero,one}   ***
+!     *****************************
+
+      zero = 0.0D0
+      one  = 1.0D0
+
+
+!     *************************
+!     ***   START ROUTINE   ***
+!     *************************
+
+      call AHFinder_fun(CCTK_FARGUMENTS)
+
+!     Find out how big is the buffer zone.  Notice that
+!     a negative value for shrink puts the masked region
+!     safely inside the horizon, while a positive value
+!     moves the masked region outside the horizon.
+
+!      shrink = getr8("ahf_maskshrink")*dx
+      shrink = ahf_maskshrink*dx
+
+!     Mask points.
+
+      do k=1,nz
+         do j=1,ny
+            do i=1,nx
+
+               if (ahfgrid(i,j,k).ge.shrink) then
+                  ahmask(i,j,k) = one
+               else
+                  ahmask(i,j,k) = zero
+               end if
+
+            end do
+         end do
+      end do
+
+
+!     ***************
+!     ***   END   ***
+!     ***************
+
+      end subroutine AHFinder_mask
+