patch niche rcb issue

src/rcb.cpp

@@ -467,6 +467,38 @@ void RCB::compute(int dimension, int n, double **x, double *wt,
       }
     }
 
+    //check if zero box width is the result due to dots being on box vertices
+    //select half of the box in this case along the best dim
+    //the best dim is chosen according to the optimum volume (to minimize surface area)
+
+    if(largest==0.0){
+      double best_volume=0;
+      double current_volume;
+      int dim1o,dim2o;
+      for (dim = 0; dim < dimension; dim++){
+        if(dim==0){
+          dim1o=1;
+          dim2o=2;
+        }
+        if(dim==1){
+          dim1o=0;
+          dim2o=2;
+        }
+        if(dim==2){
+          dim1o=0;
+          dim2o=1;
+        }
+        valuehalf = 0.5*(lo[dim] + hi[dim]);
+        current_volume = (hi[dim1o]-lo[dim1o])
+            *(hi[dim2o]-lo[dim2o])*(valuehalf-lo[dim]);
+        //chose cut that minimizes surface area by maximizing volume;
+        if(current_volume>best_volume){ best_volume = current_volume;
+        valuehalf_select = valuehalf;
+        dim_select = dim;
+        }
+      }
+    }
+
     // copy results for best dim cut into dim,valuehalf,dotmark
 
     dim = dim_select;