Empty matrix:
0 x 0 matrix:
[ ]

Zeroed 3x4 matrix:
3 x 4 matrix:
[ 0 0 0 0
  0 0 0 0
  0 0 0 0 ]

One after the other:
0 x 0 matrix:
[ ]

3 x 4 matrix:
[ 0 0 0 0
  0 0 0 0
  0 0 0 0 ]

Adding m5 and m6

4 x 4 matrix:
[ 2 2 2 2
  2 2 2 2
  2 2 2 2
  2 2 2 2 ]

4 x 4 matrix:
[ 12 12 12 12
  12 12 12 12
  12 7 12 12
  12 12 12 11 ]

The result

4 x 4 matrix:
[ 14 14 14 14
  14 14 14 14
  14 9 14 14
  14 14 14 13 ]

Attempting Gauss-Jordan reduced row echelon form.
3 x 6 matrix:
[ 1 2 1 1 0 0
  2 3 -1 0 1 0
  3 -2 -1 0 0 1 ]


3 x 6 matrix:
[ 1 0 0 0.25 0 0.25
  -0 1 0 0.05 0.2 -0.15
  0 0 1 0.65 -0.4 0.05 ]

M11 to be quartered: 

3 x 4 matrix:
[ 1 2 3 4
  5 6 7 8
  9 10 11 12 ]

UL: 

2 x 2 matrix:
[ 1 2
  5 6 ]

UR: 

2 x 2 matrix:
[ 3 4
  7 8 ]

LL: 

2 x 2 matrix:
[ 5 6
  9 10 ]

LR: 

2 x 2 matrix:
[ 7 8
  11 12 ]

Completed all simple tests.
Completed all student tests.