code: public int getValue(int c, int column) {
          if (isCompacted || c < 0 || c > MAX_CP || column < 0
                  || column >= (columns - 2)) {
              return 0;
          }
          int index = findRow(c);
          return v[index + 2 + column];
      }
docs: /*
  Always returns 0 if called after compact().