Temperature in a square plate, Neumann conditions
12 5 4
2.0  2.0
2.0  4.0
3.0  3.0
4.0  2.0
4.0  4.0
1  0.0  0.0
4  6.0  0.0
7  6.0  6.0
10 0.0  6.0
13 0.0  0.0
1  1  0.0   50.0    0.0
4  1  0.0    0.0  -50.0
7  1  0.0  -50.0    0.0
10 1  0.0    0.0   50.0
13 1  0.0   50.0    0.0