MATLAB: Can anyone please explain me this line of a code

arrayfun

probability = arrayfun(@(x) mean(audR(audR(:,1)==x,2)==2) , contrast);

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If audR is a matrix, then

audR(audR(:,1)==x,2)==2
%    ^^^^^^^^^           % first column of audR
%             ^^^        % ... is equal to x.
%    ^^^^^^^^^^^^        % used as a logical index into the rows of audR
%                 ^      % second column of audR
%                   ^^^  % ... is equal to 2.

So the code takes the rows of audR where the first column equals x, and checks if their second column equals 2.

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MATLAB: USE fft(x) as a highpass filter

Here are some suggestions for improving the code.

I have inserted several new lines of code indented from the original code, and eliminated some lines of the original code by making them into comments:

   signal=load(files{i});
      dt = 0.008;
      Fs = 1/dt;
      N = size(signal,1);
      dF = Fs/N;
      f = (-Fs/2:dF:Fs/2-dF)';
      % Band-Pass Filter:
      BPF = ((lower_freq < abs(f)) & (abs(f) < upper_freq));
      figure;
      plot(f,BPF);
   % time=0.008:0.008:size(signal,1)*0.008;
      time = dt*(0:N-1)';
      figure;
      plot(time,signal);
   % NFFT=2^nextpow2(size(signal,1));
   signal=signal-mean(signal);
   % spektrum = fft(signal,NFFT)/(size(signal,1));
      spektrum = fftshift(fft(signal))/N;
      figure;
      subplot(2,1,1);
      plot(f,abs(spektrum));
% spektrum(lower_freq:upper_freq,1)=0;
% spektrum(size(spektrum,1)- upper_freq+1:size(spektrum,1)-lower_freq+1,1)=0;
     spektrum = BPF.*spektrum;
     subplot(2,1,2);
     plot(f,abs(spektrum));
% signal=ifft(spektrum); %inverse ifft
     signal=ifft(ifftshift(spektrum)); %inverse ifft

HTH.

Rick

MATLAB: How to use FFT to get frequency of this chemical oscillator (BZ FKN reaction)

I cannot understand the file you posted. What is the time and what is the signal?

I used this code, so correct the time ‘t’ and signal ‘r’ references to your file if I have them wrong:

[d,s,r] = xlsread('Ryzx7 Run 4 FFT.xlsx');
t = d(:,3);                 % Time
r = d(:,4);                 % Signal
L = length(r);
Ts = mean(diff(t));
Fs = 1/Ts;
Fn = Fs/2;
Fr = fft(r)/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;
Iv = 1:length(Fv);
figure(1)
loglog(Fv, abs(Fr(Iv)))
grid
axis([0  180    ylim])
xlabel('Frequency (Hz)')
ylabel('Amplitude')

Best Answer

Related Solutions

MATLAB: USE fft(x) as a highpass filter

MATLAB: How to use FFT to get frequency of this chemical oscillator (BZ FKN reaction)

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