The module has 2 functions.
log_fir()
The program calculates the phase of a minimum phase discrete IIR filter having specified gain.
piir()
The program finds a n-order stable discrete IIR filter having specified phase.
Reference document
M.Kisaka: Phase design of an IIR filter and its application to an inverse system, Proceeding of the 2006 IEEE international conference on control system,Munich, Germany,Oct.2619/2622(2006)


