public static List<String> tokenize( String line )
  {    
    List<String> tokens = new LinkedList<String>();
    Pattern pat = Pattern.compile( "[a-zA-Z]+|[0-9]*\\.[0-9]+|[0-9]+|[\\+\\-\\^\\*/#\\(\\)]" );
    Matcher match = pat.matcher( line );
    while ( match.find() ) {
      tokens.add( line.substring( match.start(), match.end() ) );
    }
    if ( tokens.size() > 0 ) {
      return tokens;
    }
    else return null;
  }