|1 q + L | ≥ bbq
Since p11 and p22 are elements of the principal diagonal of P, then Eq (5.85) is the diagonal dominance condition for the 2x2 plant. Equation (5.85(a)) must also be satisfied for all frequencies. This condition is obtained considering only the left column of the MISO loops for the 2x2 plant of Fig 5.11. This condition may also be obtained by using the right column of the MISO loops in Fig 5.11 since
the loop transmissions L1 and L2 are again involved in the derivation. If Eq. (5.85) is not satisfied then refer to Item 3 in the summary of Example 6.6.