mat( ( 1,-1, 0, 0, 0, 0, 0, 0), ( 0, 1,-1, 0, 0,-1, 0, 0), ( 0, 0, 1,-1, 0, 0, 0, 0), ( 0, 0, 0, 1,-1, 0, 0, 0), ( 0, 0, 0, 0, 0, 1,-1, 0), ( 0, 0, 0, 0, 0, 0, 1,-1), ( -1, 0, 0, 0, 0, 0, 0, 0), ( 0, 0, 0, 0, 1, 0, 0, 0), ( 0, 0, 0, 0, 0, 0, 0, 1 ) )