Conjectured Properties

The following conjectures are true for analog positive-real functions, but no rigorous attempt was made to establish them in the discrete-time case.

• If all poles and zeros of a PR function are on the unit circle, then they alternate along the circle.

• If $B(z)/A(Z)$ is PR, then so is $B^\prime(z)/A^\prime(z)$, where the prime denotes differentiation in $z$.