comnum.cumulants

comnum.cumulants(x)

The sample cumulants of order two and four of a zero-mean signal, and the normalised C40/C21², C42/C21² (Swami & Sadler 2000).

Parameters:

x (array_like) – the samples (complex).

Returns:

c20, c21, c40, c41, c42, c40_normalized, c42_normalized.

Return type:

dict

Raises:

ValueError – for an invalid parameter or input (the message names it).

Examples

>>> import comnum, numpy as np
>>> c = comnum.Constellation("qam", 4).normalized()
>>> round(comnum.cumulants(np.tile(c.points, 100))["c42_normalized"], 6)
-1.0