Plot 3D matrix with complex values

I have a matrix of complex values (a i +b), with shape 128 * 8 * 121. How can I plot it, please ?

Thank you so much in advance :)

[darova]

What those values represent?

[nour besbes]

It represent the result of the stft matlab function

[darova]

Where those values should be on the graph?

[nour besbes]

I want to have a graph like this one.

[darova]

What do dimension mean? (128 x 8 x 121) ?

[nour besbes]

it's a 3D matrix. It means 8 matrix of (128 rows X 121 columns ) size.

Answer 1

[Matt J]

One way,

plot(a(:),b(:),'x')

Answer 2

[darova]

Try pcolor

pcolor(A(:,1,:))            % display first matrix

Answer 3

[Sara James]

As another mentioned previously, use pcolor. Note that since your signal is complex, you will have to take the absolute value first as follows:

fs = 3000; % Sampling frequency (Hz)
t = 0:1/fs:1-1/fs; % Time (sec)
x = [exp(2j*pi*100*cos(2*pi*2*t))+randn(size(t))/100; ...
    exp(2j*pi*100*cos(0.5*pi*2*t))+randn(size(t))/100; ...
    exp(2j*pi*100*cos(1*pi*2*t))+randn(size(t))/100]'; % Multi-channel signal
  
[S,F,T] = stft(x,fs,'Window',hamming(128,'periodic'),'OverlapLength',50);
smag = mag2db(abs(S)); % Convert to dB
caxisLims = max(smag(:)) + [-60 0]; % Color axis limits
figure('Name','STFT')
numChannels = size(x,2);
for ii = 1:numChannels
    subplot(2,2,ii)
    pcolor(T,F,smag(:,:,ii))
    xlabel('Time (s)')
    ylabel('Frequency (Hz)')
    shading flat
    hC = colorbar;
    hC.Limits = caxisLims;
    hC.Label.String = 'Magnitude (dB)';
    title(sprintf('Channel %d',ii))
end
sgtitle('Spectrogram')