gftool.basis.ZeroPole

class gftool.basis.ZeroPole(zeros: ndarray, poles: ndarray, amplitude: complex = 1.0)

Rational polynomial characterized by zeros and poles.

The function is given by ZeroPole.eval(z) = amplitude * np.prod(z - zeros) / np.prod(z - poles)

Parameters:

zeros, poles(…, Nz), (…, Np) complex np.ndarray

Zeros and poles of the represented function.

amplitude(…) complex np.ndarray or complex

The amplitude of the function. This is also the large abs(z) limit of the function ZeroPole.eval(z) = amplitude * z**(Nz-Np).

__init__(*args, **kwargs)

Methods

__init__(*args, **kwargs)
count(value, /)	Return number of occurrences of value.
eval(z)	Evaluate the function at z.
index(value[, start, stop])	Return first index of value.
reciprocal(z)	Evaluate the reciprocal 1./ZeroPole.eval(z) at z.
to_ratpol()	Represent the rational polynomial as fraction of two polynomial.

Attributes

amplitude	Amplitude of the function, i.e., the prefactor.
poles	Poles of the rational polynomial.
zeros	Zeros of the rational polynomial.