code: final static boolean arrayRegionMatches(char[] source, int sourceStart,
                                              char[] target, int targetStart,
                                              int len)
      {
          int sourceEnd = sourceStart + len;
          int delta = targetStart - sourceStart;
          for (int i = sourceStart; i < sourceEnd; i++) {
              if (source[i] != target[i + delta])
              return false;
          }
          return true;
      }
docs: Convenience utility to compare two arrays of doubles.
  @param len the length to compare.
  The start indices and start+len must be valid.