`scipy.signal._filter_design:buttap`

Signature

def buttap(N, *, xp = None, device = None)

Return (z,p,k) for analog prototype of Nth-order Butterworth filter.

The filter will have an angular (e.g., rad/s) cutoff frequency of 1.

N : int: The order of the filter
xp : array_namespace, optional: Optional array namespace. Should be compatible with the array API standard, or supported by array-api-compat. Default: numpy
device : any: optional device specification for output. Should match one of the supported device specification in xp.

z : ndarray[float64]: Zeros of the transfer function. Is always an empty array.
p : ndarray[complex128]: Poles of the transfer function.
k : float: Gain of the transfer function.