$matrix = array
    (
        array(80,  -1, 167,  70,  56, 141, 226, 301, 364, 136),
        array(126, 167,  -1, 200, 113, 202, 119, 131, 198, 125),
        array(324, 364, 198, 398, 310, 399, 213,  97,  -1, 236),
        array(55, 136, 125,  91,  85, 170,  91, 263, 236,  -1),
    );
    $rows = array
                   ("Davenport",
                     "Des Moines",
                     "Sioux City",
                     "Waterloo"
                    );
    $cols = array
                    ("Cedar Rapids",
                     "Davenport",
                     "Des Moines",
                     "Dubuque",
                     "Iowa City",
                     "Keokuk",
                     "Mason City",
                     "Omaha",
                     "Sioux City",
                     "Waterloo"
);