REBIN:matrix

1_example

              1  2  3  4  5  6
              2  4  6  8 10 12
              3  6  9 12 15 18
              4  8 12 16 20 24
 Suppose M =  5 10 15 20 25 30   After the command: REBIN M MOUT 2 3
              6 12 18 24 30 36
              7 14 21 28 35 42
              8 16 24 32 40 48

            18  45   Note that: MOUT[1,1] = 1+2+3 + 2+4+6 
            42 105              MOUT[1,2] = 4+5+6 + 8+10+12 
   MOUT =   66 165              MOUT[2,1] = 3+6+9 + 4+8+12 
            90 225              MOUT[2,2] = 12+15+18 + 16+20+24,  etc.