If you're using pyplot.specgram (i.e. "from pylab import *;
specgram(...)"), note that the plot is in dB, hence the negative
values.
I'm surprised this fact isn't mentioned in the documentation:
http://matplotlib.org/api/pyplot_api.html?highlight=specgram#matplotlib.pyplot.specgram
However, when i
Hi,
If you trace back into the code further, you will see that the Pxx is
computed as X = fft(x), Pxx = X * conj(X) which is real, but the data
type will be complex with a ~0 imaginary part (up to floating point
precision). Thus the Pxx.real is just to ensure that the resulting
data type is real in
Hi,
not 100% sure this is a bug, but here goes:
In file matplotlib/lib/matplotlib/mlab.py, the functions psd (power spectral
density) and specgram returns the real part of the fourier transform.
% grep -n Pxx.real mlab.py
390:return Pxx.real,freqs
470:Pxx = Pxx.real #Needed since helper
