rank 0: [0,0:2]      0      1      2      3      4      5      6      7      8      9
rank 0: [1,0:2]     10     11     12     13     14     15     16     17     18     19
rank 1: [2,0:2]     20     21     22     23     24     25     26     27     28     29
rank 1: [3,0:2]     30     31     32     33     34     35     36     37     38     39
rank 2: [4,0:3]     40     41     42     43     44     45     46     47     48     49
rank 2: [5,0:3]     50     51     52     53     54     55     56     57     58     59
rank 2: [6,0:3]     60     61     62     63     64     65     66     67     68     69
