# Matrix dimensions must agree error

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Jordan Reece Duggan el 9 de Mzo. de 2021
Comentada: Jordan Reece Duggan el 12 de Mzo. de 2021
Hi all,
Ive got some code from my tutor thats meant to be filtering a medical signal (ecc) by multiplication in the frequency domain, all goes well till Y5=X5.*HBR; , there it says matrix dimensions must agree, been rattling my head about this for a while but cant figure out where the conflict is, tutor wont help either.
fs=500;
n=2;
Wn=40/250;
[B, A] = butter(n,Wn);
printsys(B, A, 'z' );
x1=eye(1,1000); % create an impulse
plot(x1)
pause
hb=filter(B, A, x1); % calculate the impulse response of the Butterworth filter
plot(hb)
pause
freqz(B, A, 1024, fs)% create frequency response plots
set(gca, 'XScale', 'log')
pause
medical = 'medical signal.dat'; %this needs to be the location of the waveform
plot(xmed) % display the noisy waveform
pause
X5=fft(xmed)/length(xmed); % calculate the FFT of the signal
f=fs/length(X5)*(0:length(X5)-1);
plot(f, abs(X5)); % display the signal spectrum
pause
HBC = fft(hb)/length(hb); % calculate the FFT of the filter impulse response
HBR = HBC.' ; % convert the result to a row vector
f=fs/length(HBR)*(0:length(HBR)-1);
plot(f, abs(HBR)); % display the magnitude of the filter frequency response
pause
Y5 = X5.'HBR; % multiply the signal fft by the filter frequency response
plot(f,Y5) % display the frequency response of the result
pause
y5=ifft(Y5)*(length(Y5))^2; % convert the result back into the time domain
plot(y5) % display the filtered waveform
pause
Any suggestions on whats causing the matrixes to conflict?
Cheers
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KSSV el 10 de Mzo. de 2021
This lineL
Y5 = X5.'HBR; % multiply the signal fft by the filter frequency response
is not correct. You need to change it.
Learn about debugging and check the dimensions where you are getting error.

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Prudhvi Peddagoni el 12 de Mzo. de 2021
Hi,
You can keep breakpoints in the code and check the values in different variables.
Hope this helps.
##### 1 comentarioMostrar -1 comentarios más antiguosOcultar -1 comentarios más antiguos
Jordan Reece Duggan el 12 de Mzo. de 2021
It did thanks!

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