pydsm.delsig.evalTF

pydsm.delsig.evalTF(tf, x)

Evaluates a transfer function.

This function can be used either for discrete time or continuous time transfer functions (see the notes).

Parameters

tftuple

transfer function in zpk or ba form

xcomplex or array_like of complex

value or vector of values where the tf is to be evaluated

Returns

yndarray

value(s) of transfer function at the given complex values.

Notes

Parameter x corresponds to ‘s’ or ‘z’ in CT or DT transfer functions respectively. Thus it should be 1j*omega or exp(1j*omega*T).

With respect to the tf parameter, zpk form is a triple containing a list of zeros, a list of poles and a scalar gain. The ba form (also called tf form in the scipy documentation) is a couple containing a list of the numerator coefficients and a list of the denominator coefficients. The coefficients are sorted from the higher power of ‘s’ or ‘z’ to the lower, so that the last coefficient is in fact the constant term in the numerator/denominator polynomial.