add patch::edge_adjacent_to_patch()

git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinderDirect/trunk@156 f88db872-0e4f-0410-b76b-b9085cfa78c5

2 files changed, 74 insertions, 0 deletions

diff --git a/src/patch/patch.cc b/src/patch/patch.cc
index 5f20b10..aee20f6 100644
--- a/src/patch/patch.cc
+++ b/src/patch/patch.cc
@@ -7,6 +7,7 @@
 // z_patch::z_patch
 // x_patch::x_patch
 // y_patch::y_patch
+// patch::edge_adjacent_to_patch
 //
 // patch::setup_mirror_symmetry_ghost_zone
 // patch::setup_periodic_symmetry_ghost_zone
@@ -146,6 +147,74 @@ y_patch::y_patch(patch_system &my_patch_system_in, int patch_number_in,
 		grid_array_pars_in, pars_in, N_gridfns_in)
 
 //*****************************************************************************
+
+//
+// This function finds which patch edge is adjacent to a neighboring
+// patch q, or do an error_exit() if q isn't actually a neighboring patch.
+// The computation is done using only (rho,sigma) coordinate sets and
+// min/max dang bounds ==> it's ok to use this function in setting up
+// interpatch ghost zones.
+//
+const patch_edge& patch::edge_adjacent_to_patch(const patch &q) const
+{
+const patch &p = *this;
+
+// which (rho,sigma) coordinate do the patches have in common?
+local_coords::coords_set common_coord_set
+	= p.coords_set_rho_sigma() & q.coords_set_rho_sigma()
+
+// is this coordinate rho or sigma in each patch?
+bool common_is_p_rho   = common_coord_set == p.coords_set_rho  ();
+bool common_is_p_sigma = common_coord_set == p.coords_set_sigma();
+if ((common_is_p_rho ^ common_is_p_sigma) != 0x1)
+   then error_exit(ERROR_EXIT,
+"***** patch::edge_adjacent_to_patch():\n"
+"        common coordinate isn't exactly one of p.{rho,sigma}!\n",
+"        p.name()=\"%s\" q.name()=\"%s\"\n"
+"        common_coord_set=%s\n"
+"        common_is_p_rho=%d common_is_p_sigma=%d\n"
+,
+		   p.name(), q.name(),
+		   local_coords::name_of_coords_set(common_coord_set),
+		   int(common_is_p_rho), int(common_is_p_sigma));
+								/*NOTREACHED*/
+bool common_is_q_rho   = common_coord_set == q.coords_set_rho  ();
+bool common_is_q_sigma = common_coord_set == q.coords_set_sigma();
+if ((common_is_q_rho ^ common_is_q_sigma) != 0x1)
+   then error_exit(ERROR_EXIT,
+"***** patch::edge_adjacent_to_patch():\n"
+"        common coordinate isn't exactly one of q.{rho,sigma}!\n",
+"        p.name()=\"%s\" q.name()=\"%s\"\n"
+"        common_coord_set=%s\n"
+"        common_is_q_rho=%d common_is_q_sigma=%d\n"
+,
+		   p.name(), q.name(),
+		   local_coords::name_of_coords_set(common_coord_set),
+		   int(common_is_q_rho), int(common_is_q_sigma));
+								/*NOTREACHED*/
+
+// is the common boundary min/max in each patch?
+bool common_is_p_min_q_max
+    = fuzzy_EQ(p.min_dang(common_is_p_rho), q.max_dang(common_is_q_rho));
+bool common_is_p_max_q_min
+    = fuzzy_EQ(p.max_dang(common_is_p_rho), q.min_dang(common_is_q_rho));
+if ((common_is_p_min_q_max ^ common_is_p_max_q_min) != 0x1)
+   then error_exit(ERROR_EXIT,
+"***** patch::edge_adjacent_to_patch():\n"
+"        common coordinate isn't exactly one of {pmax/qmin, pmin/qmax}!\n"
+"        p.name()=\"%s\" q.name()=\"%s\"\n"
+"        common_coord_set=%s\n"
+"        common_is_p_min_q_max=%d common_is_p_max_q_min=%d\n"
+,
+		   p.name(), q.name(),
+		   local_coords::name_of_coords_set(common_coord_set),
+		   int(common_is_p_min_q_max), int(common_is_p_max_q_min));
+								/*NOTREACHED*/
+
+return p.minmax_ang_patch_edge(common_is_p_min_q_max, common_is_p_rho);
+}
+
+//*****************************************************************************
 //*****************************************************************************
 //*****************************************************************************
 
diff --git a/src/patch/patch.hh b/src/patch/patch.hh
index 5e8a9c8..97b56da 100644
--- a/src/patch/patch.hh
+++ b/src/patch/patch.hh
@@ -250,6 +250,11 @@ public:
 					    : max_sigma_patch_edge());
 		}
 
+	// find which patch edge is adjacent to neighboring patch,
+	// or error_exit() if it's not actually a neighboring patch
+	// ... computation done using only (rho,sigma) coordinate sets
+	// and min/max dang bounds ==> ok to use in setting up ghost zones
+	const patch_edge& edge_adjacent_to_patch(const patch& q) const;
 
 	//
 	// ***** ghost zones *****