rework yet again how we set up ghost zone iperp mapping

to try and cure problems with empty ghost zones causing assertion failures
from out-of-range mappings --> still not working... :(


git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinderDirect/trunk@291 f88db872-0e4f-0410-b76b-b9085cfa78c5

1 files changed, 24 insertions, 18 deletions

diff --git a/src/patch/ghost_zone.cc b/src/patch/ghost_zone.cc
index fe65b7a..0e780c4 100644
--- a/src/patch/ghost_zone.cc
+++ b/src/patch/ghost_zone.cc
@@ -264,33 +264,39 @@ if (! local_coords::fuzzy_EQ_ang(my_edge().grid_outer_perp(),
 // set up the iperp interpatch coordinate mapping
 //
 
-// compute the  other_iperp  corresponding to  inner_iperp
-// using the fact that  perp  is the same coordinate in both cases
-// (modulo 2*pi radians = 360 degrees)
-const fp inner_perp = my_edge().perp_of_iperp(inner_iperp());
-const fp other_inner_perp
-	= other_patch().modulo_reduce_ang(other_edge().perp_is_rho(),
-					  inner_perp);
-const fp fp_other_inner_iperp = other_edge()
-				.fp_iperp_of_perp(other_inner_perp);
+// compute the iperp --> other_iperp mapping for a sample point;
+// ... if the ghost zone is empty, then the sample point will necessarily
+//     be out-of-range in the ghost zone, so we use the *unchecked*
+//     conversions to avoid errors in this case
+// ... we do the computation using the fact that  perp  is the same
+//     coordinate in both patches (modulo 2*pi radians = 360 degrees)
+const int sample_iperp = outer_iperp();
+const fp sample_perp = my_edge().perp_map()
+				.fp_of_int_unchecked(sample_iperp);
+						// unchecked conversion here!
+const fp other_sample_perp = other_patch()
+			     .modulo_reduce_ang(other_edge().perp_is_rho(),
+						sample_perp);
+const fp fp_other_sample_iperp = other_edge()
+				 .fp_iperp_of_perp(other_sample_perp);
 
 // verify that this is fuzzily a grid point
-if (! fuzzy<fp>::is_integer(fp_other_inner_iperp))
+if (! fuzzy<fp>::is_integer(fp_other_sample_iperp))
    then error_exit(ERROR_EXIT,
 "***** interpatch_ghost_zone::interpatch_ghost_zone:\n"
 "        my_patch().name()=\"%s\" my_edge().name()=%s\n"
 "        other_patch().name()=\"%s\" other_edge().name()=%s\n"
-"        inner_iperp()=%d inner_perp=%g\n"
-"        other_inner_perp=%g\n"
-"        ==> fp_other_inner_iperp=%g isn't fuzzily an integer\n"
+"        sample_iperp=%d sample_perp=%g\n"
+"        other_sample_perp=%g fp_other_sample_iperp=%g\n"
+"        ==> fp_other_sample_iperp isn't fuzzily an integer!\n"
 "        ==> patches aren't commensurate in the perpendicular coordinate!\n"
 ,
 		   my_patch().name(), my_edge().name(),
 		   other_patch().name(), other_edge().name(),
-		   inner_iperp(), double(inner_perp),
-		   double(other_inner_perp),
-		   double(fp_other_inner_iperp));		/*NOTREACHED*/
-const int other_inner_iperp = round<fp>::to_integer(fp_other_inner_iperp);
+		   sample_iperp, double(sample_perp),
+		   double(other_sample_perp),
+		   double(fp_other_sample_iperp));		/*NOTREACHED*/
+const int other_sample_iperp = round<fp>::to_integer(fp_other_sample_iperp);
 
 // compute the +/- sign (direction) of the iperp --> other_iperp mapping
 //
@@ -306,7 +312,7 @@ const double iperp_map_sign_pm1
 // now we finally know enough to set up the iperp interpatch coordinate mapping
 other_iperp_ = new cpm_map<fp>
 			  (min_iperp(), max_iperp(),
-			   inner_iperp(), other_inner_iperp,
+			   sample_iperp, other_sample_iperp,
 			   (iperp_map_sign_pm1 > 0.0) ? cpm_map<fp>::plus_map
 						      : cpm_map<fp>::minus_map);