[Eigen]Blocking

    mxd::t m(4,4);
    m << 1,  2,   3,  4,
         5,  6,   7,  8,
         9,  10,  11, 12,
         13, 14,  15, 16;
 
    co("Block in the middle");
    co(m.block<2,2>(1,1) , " block : ");
 
    for(z::t i(1) ; i <= 3; ++i ){
        co(i,"block of size :");
        co(m.block(0,0,i,i));
    }

1 by 1 to 3 by 3 block

result :

Block in the middle
 block :  = 
 6  7
10 11
block of size : = 
1
output = 
1
block of size : = 
2
output = 
1 2
5 6
block of size : = 
3
output = 
 1  2  3
 5  6  7
 9 10 11

block replacing :

    mxd::t m(4,4);
    m << 1,  2,   3,  4,
         5,  6,   7,  8,
         9,  10,  11, 12,
         13, 14,  15, 16;
 
    m2d::t m2;
    m2 << 1, 1, 1, 1;
 
    m.block(0,0,2,2) = m2;
 
    co(m, "block replaced.!");
 
 

result

block replaced.! = 
 1  1  3  4
 1  1  7  8
 9 10 11 12
13 14 15 16