A = size 12 by 12 Matrix of double:
[ 3 -1 0 0 -1 0 0 0 0 0 0 0 ]
[ -1 4 -1 0 0 -1 0 0 0 0 0 0 ]
[ 0 -1 4 -1 0 0 -1 0 0 0 0 0 ]
[ 0 0 -1 3 0 0 0 -1 0 0 0 0 ]
[ -1 0 0 0 4 -1 0 0 -1 0 0 0 ]
[ 0 -1 0 0 -1 5 -1 0 0 -1 0 0 ]
[ 0 0 -1 0 0 -1 5 -1 0 0 -1 0 ]
[ 0 0 0 -1 0 0 -1 4 0 0 0 -1 ]
[ 0 0 0 0 -1 0 0 0 3 -1 0 0 ]
[ 0 0 0 0 0 -1 0 0 -1 4 -1 0 ]
[ 0 0 0 0 0 0 -1 0 0 -1 4 -1 ]
[ 0 0 0 0 0 0 0 -1 0 0 -1 3 ]

B = size 12 by 3 Matrix of double:
[ 1 2 3 ]
[ 2 4 6 ]
[ 3 6 9 ]
[ 4 8 12 ]
[ 5 10 15 ]
[ 6 12 18 ]
[ 7 14 21 ]
[ 8 16 24 ]
[ 9 18 27 ]
[ 10 20 30 ]
[ 11 22 33 ]
[ 12 24 36 ]

A*B (sparse) = size 12 by 3 Matrix of double:
[ -4 -8 -12 ]
[ -2 -4 -6 ]
[ -1 -2 -3 ]
[ 1 2 3 ]
[ 4 8 12 ]
[ 6 12 18 ]
[ 7 14 21 ]
[ 9 18 27 ]
[ 12 24 36 ]
[ 14 28 42 ]
[ 15 30 45 ]
[ 17 34 51 ]

A*B (dense) = size 12 by 3 Matrix of double:
[ -4 -8 -12 ]
[ -2 -4 -6 ]
[ -1 -2 -3 ]
[ 1 2 3 ]
[ 4 8 12 ]
[ 6 12 18 ]
[ 7 14 21 ]
[ 9 18 27 ]
[ 12 24 36 ]
[ 14 28 42 ]
[ 15 30 45 ]
[ 17 34 51 ]

