| (Ex )zt+1 - (Ex )zt | = | (Hy )z+½t+½ - (Hy )z-½t+½ |
| ———————— | – ———————————— | |
| Δt | εz Δz |
| (Hy )z+½t+½ - (Hy )z+½t-½ | = | (Ex )z+1t - (Ex )zt |
| ———————————— | – ———————— | |
| Δt | Δz |
| r12 = | Er | = | ε1½ - ε2½ | = | - 1 |
| —— | —————— | —— | |||
| E | ε1½ + ε2½ | 3 |
| t12 = | Et | = | 2 ε1½ | = | 2 |
| —— | —————— | —— | |||
| E | ε1½ + ε2½ | 3 |