Index: src/LinearExtrapBnd.c
===================================================================
RCS file: /cactusdevcvs/CactusExamples/SampleBoundary/src/LinearExtrapBnd.c,v
retrieving revision 1.10
diff -u -r1.10 LinearExtrapBnd.c
--- src/LinearExtrapBnd.c	3 Jun 2004 15:17:23 -0000	1.10
+++ src/LinearExtrapBnd.c	2 Nov 2005 00:51:24 -0000
@@ -116,6 +116,7 @@
       -8  potentially valid table handle
       -16 dimension is not supported
       -32 possibly called with a grid scalar
+      -64 not enough local grid points
    @endreturndesc
 @@*/
 
@@ -124,7 +125,7 @@
 {
   int i, j, gi, gtype, dim, retval, err;
   int doBC[6];
-  const int *lsh, *bbox;
+  const int *lsh, *bbox, *ghosts;
   CCTK_INT symtable;
   CCTK_INT symbnd[6];
   CCTK_INT is_physical[6];
@@ -178,6 +179,7 @@
       dim = GH->cctk_dim;
       bbox = GH->cctk_bbox;
       lsh = GH->cctk_lsh;
+      ghosts = GH->cctk_nghostzones;
     }
     else
     {
@@ -192,6 +194,7 @@
       dim = group_data.dim;
       bbox = group_data.bbox;
       lsh = group_data.lsh;
+      ghosts = group_data.nghostzones;
     }
     var_ptr = GH->data[vars[i]][0];
 #ifdef DEBUG
@@ -220,7 +223,7 @@
     /* Decide on which faces the bc should be applied */
     for (j=0; j<2*dim; ++j)
     {
-      doBC[j] = lsh[j/2] > widths[i]+2 && bbox[j];
+      doBC[j] = bbox[j];
     }
 
     /* see if we have a physical boundary */
@@ -239,8 +242,24 @@
       doBC[j] &= is_physical[i];
     }
 
+    /* Check whether there are enough grid points */
+    for (j=0; j<2*dim; ++j)
+    {
+      if (doBC[j])
+      {
+        if (lsh[j/2] - ghosts[j/2] < widths[j/2] + 2)
+        {
+          CCTK_VWarn (1, __LINE__, __FILE__, CCTK_THORNSTRING,
+                      "Not enough local grid points.  "
+                      "Not applying bc.");
+          retval |= 64;
+        }
+      }
+    }
+    
+
     /* Apply the boundary condition */
-    if( !( retval & ( 1 | 16 ) ) ) /* unless particularly bad errors */
+    if( !( retval & ( 1 | 16 | 64 ) ) ) /* unless particularly bad errors */
       CCTK_FNAME(Linear_extrap_one_bndry)(doBC, lsh, var_ptr);
   }