para:
THDD difference formula THD
THDS harmonic series THD
TIF Telephone Influence Factor
THF Telephone Harmonic Factor
TDD Total Demand Distortion
TRD Total Rated Distortion
HPHASE Series harmonic phase
harmonic:
individual harmonic for display
max:
length of harmonic series (to 50)
It is not necessary to send any
arguments, but if any are sent they must
be in the specified order.