showParseval

#!/usr/bin/env python
import numpy as np

# Specify length of signal
N = 512;

# Generate time domain signal
x = np.random.rand(N).astype('complex')

# Evaluate signal power in the time domain
pTD = np.inner(np.conj(x),x)

# Transform signal to frequency domain
X = np.fft.fft(x)

# Calculate signal power in the frequency domain
pFD = np.inner(np.conj(X),X)/N

# pTD must = pFD
print "Time Domain Power = " + str(pTD)
print "Freq Domain Power = " + str(pFD)

Python snippet to show power equivalence between the time domain and frequency domain representation of a discrete signal. An implementation Parseval's Theorem.