#This error occurred while using colorbar with spectrogram.
#Below is an extract of the code that caused an ValueError:
vmin = 10*np.log10(np.max(signalArr)) - 100
NFFT = 1024
pxx, freq, t, cax = ax.specgram(signalArr**2/(NFFT/2), Fs=fs,
mode='psd', NFFT=NFFT, noverlap=NFFT/2, vmin=vmin, cmap=cmap)
clb= fig.colorbar(cax)
#initially the vmin was set as above for specgram, upon executing the
#code above, it let to the ValueError, then error was fixed after vmin
#was set to:
vmin = 10*np.log10(np.max(signalArr)) - 200
#Note that this error depend on the signal signalArr.