code: public static boolean childContains(double[][] child, double value, double delta) {
          for (int i=0; i<child.length; i++) {
              for (int j=0; j<child.length; j++) {
                  if (i == j) { continue; }
                  if (Primitives.equals(child[i][j], value, delta)) {
                      return true;
                  }
              }
          }
          return false;
      }
docs: Safely checks whether the child array contains a value -- ignoring diagonal entries.