| node 1 | node 2 | node 3 | node 4 |
node 1 | Ka | −Ka | 0 | 0 |
node 2 | −Ka | Ka + Kb + Kc | −Kb | −Kc |
node 3 | 0 | −Kb | Kb + Kd | −Kd |
node 4 | 0 | −Kc | Kd | Kc − Kd |