Matrix dimensions must agree when doing an elementwise operation

Question

Adrien Sallé 2022-4-11

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评论： Adrien Sallé 2022-4-18

Hello, I would like to compute the product of two Fourier transform with the following code :

Fe=8000;        
Te=1/Fe;          
N=Fe;               
t=0:Te:(N-1)*Te;       
T=0.02;                  
x=1+square(2*pi*t/T);  
K=10;
h=ones(1,K)/K;           
y=conv(x,h);           
Npts=Fe*T;               
X=fft(x);
H=fft(h);
Y=fft(y);
prod=X.*H;
conv=fft(conv(x,h,'same'));

The objective here is to show that fft(h)*fft(x)= fft(conv(x,h)).

The problem is that even if I use the elementwise operator I get this error :

This is surely because of the size of the vector h, could anyone explain me what's wrong ?

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Torsten 2022-4-11

X has 8000, H has 10 elements. There is no way to multiply the arrays.

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Answer 1

Esha Chakraborty 2022-4-14

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Hi Adrien,

I understand that you are encountering the error - 'Matrix dimensions must agree', while performing element-wise matrix multiplcation of X and H variables in your code.

Please note that for matrix multiplcation, the sizes of X and H must be the same or be compatible. You can find more details on array size compatibility in the documentation here.