From c084ab2dd816d0e5bf0c02f9e3626b1ad297274d Mon Sep 17 00:00:00 2001
From: schnetter <schnetter@f69c4107-0314-4c4f-9ad4-17e986b73f4a>
Date: Tue, 8 Apr 2008 23:11:02 +0000
Subject: Add two new parameters onesided_outer_boundaries and
 onesided_interpatch_boundaries.  These decide whether the user wants
 one-sided differencing stencil near outer and near multi-patch boundaries. 
 Both default to yes for backward compatibility.

git-svn-id: https://svn.cct.lsu.edu/repos/numrel/LSUThorns/SummationByParts/trunk@96 f69c4107-0314-4c4f-9ad4-17e986b73f4a
---
 param.ccl     |  8 ++++++++
 src/stencil.c | 35 ++++++++++++++++++++---------------
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/param.ccl b/param.ccl
index 32cb36e..0430e02 100644
--- a/param.ccl
+++ b/param.ccl
@@ -18,6 +18,14 @@ INT order "Order of accuracy" STEERABLE=always
   2:8:2 :: ""
 } 2
 
+BOOLEAN onesided_outer_boundaries "Use one-sided stencils near outer boundaries" STEERABLE=always
+{
+} "yes"
+
+BOOLEAN onesided_interpatch_boundaries "Use one-sided stencils near inter-patch boundaries" STEERABLE=always
+{
+} "yes"
+
 BOOLEAN use_dissipation "Should we add dissipation"
 {
 } "no"
diff --git a/src/stencil.c b/src/stencil.c
index e57f9ff..ca837c6 100644
--- a/src/stencil.c
+++ b/src/stencil.c
@@ -1,4 +1,5 @@
 #include "cctk.h"
+#include "cctk_Parameters.h"
 
 #include "util_ErrorCodes.h"
 #include "util_Table.h"
@@ -9,13 +10,15 @@
 
 /* Determine whether a boundary with the symmetry handle symbnd is a
    "regular" symmetry boundary (where the SBP stencils should not be
-   modified), or an outer boundary (or a multi-block boundary), where
+   modified), or an outer boundary (or a multi-patch boundary), where
    the SBP stencils need to be modified.  */
 
 void SBP_determine_onesided_stencil (const cGH * cctkGH, int * onesided)
 {
+  DECLARE_CCTK_PARAMETERS;
+  
   int symtable;
-  int pen_sym_handle;
+  int mp_sym_handle;
   CCTK_INT symbnd[6];
   int ierr;
   int d;
@@ -30,7 +33,7 @@ void SBP_determine_onesided_stencil (const cGH * cctkGH, int * onesided)
     CCTK_WARN(0,"Cannot get symmetry handles");
   }
   
-  pen_sym_handle = SymmetryHandleOfName ( "multipatch" );
+  mp_sym_handle = SymmetryHandleOfName ( "multipatch" );
   
   for (d=0; d<6; ++d) {
     if (! cctkGH->cctk_bbox[d]) {
@@ -38,21 +41,23 @@ void SBP_determine_onesided_stencil (const cGH * cctkGH, int * onesided)
       onesided[d] = 0;
     } else {
       /* On an outer boundary (which is not a symmetry boundary),
-         symbnd < 0.  */
+         symbnd < 0 */
       if (symbnd[d] < 0) {
-        onesided[d] = 1;
+        /* Use one-sided stencils near outer boundaries if the user
+           wants it so */
+        onesided[d] = onesided_outer_boundaries;
       } else {
-        if (pen_sym_handle >= 0) {
-          /* If the symmetry boundary is a multi-block boundary, then
-             symbnd = pen_sym_handle.  However, we can only check that
-             thorn MultiPatch is active, i.e., whether pen_sym_handle
-             >= 0.  */
-          if (symbnd[d] == pen_sym_handle) {
-            onesided[d] = 1;
-          } else {
-            onesided[d] = 0;
-          }
+        /* If the symmetry boundary is a multi-patch boundary, then
+           symbnd = mp_sym_handle.  However, we can only check this if
+           a multi-patch thorn is active, i.e., when mp_sym_handle >=
+           0 */
+        if (mp_sym_handle >= 0 && symbnd[d] == mp_sym_handle) {
+          /* Use one-sided stencils near inter-patch boundaries if the
+             user wants it so */
+          onesided[d] = onesided_interpatch_boundaries;
         } else {
+          /* Always use centred stencils near regular symmetry
+             boundaries (e.g. a reflection symmetry) */
           onesided[d] = 0;
         }
       }
-- 
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