rfader

Evaluates over the frequency range kv.the derivative of order m of the rational function approximation: [cnum[-1] + cnum[-2] z + … + cnum[0] z**Nnum ]/…

[cden[-1] + cden[-2] z + … + cden[0] z**Nden]

where the numerator and denominator polynomial orders, Nnum and Nden, are the length of the cnum and cden arrays and:

• z=exp(1.j*kv*ds), with ds sampling time if ds is given (discrete-time

system) - z=1.*kv, if ds is None (continuous time system)