Mistake in the red-noise spectrum

[citrux]

pycwt/pycwt/wavelet.py

Lines 252 to 257 in 1bef44e

	# Theoretical discrete Fourier power spectrum of the noise signal
	# following Gilman et al. (1963) and Torrence and Compo (1998),
	# equation 16.
	def pk(k, a, N):
	return (1 - a ** 2) / (1 + a ** 2 - 2 * a * np.cos(2 * np.pi * k / N))
	fft_theor = pk(freq, alpha, n0)

According to equation 16 from Torrence and Compo (1998) this code should look like this

def pk(k, a, N): 
    return (1 - a ** 2) / (1 + a ** 2 - 2 * a * np.cos(2 * np.pi * k / N)) 
fft_theor = pk(freq, alpha, 1) 

This bug leads to different results of usage of significance function with signal and its variance.