cannot use element wise operator in frequency response?

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SimTec
SimTec 2022-8-24
评论： Bruno Luong 2022-8-24
Hi guys,
I am trying to get the requency response of the averaging FIR filter using the element wise operator, code below:
Fs=8e3; % sampling frequency
Fc=170; % cutoff frequency
alpha=1-2*pi*Fc/Fs;
nb=round(log2(1/(1-alpha))); % number of shift to the right correspending to multiplication by alpha
NbPoints=1000;
Ndec=Fs/2/1000;
Fstart=1;
i=1:Ndec*NbPoints;
freq=Fstart*10.^(i/NbPoints);
H_f=(1-alpha)*cos(pi.*freq/Fs)/sqrt(1+(alpha^2)-2*alpha*cos(2*pi.*freq/Fs));
semilogx(freq,20*log10(abs(H_f)))
the problem the H_f provides me only one output and not the vector result. how can I fix this.
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SimTec
SimTec 2022-8-24
my bad. I just corrected it.. I still do not get the value of the H_f as a vector
Bruno Luong
Bruno Luong 2022-8-24
The division "/" before sqrt is NOT elemetwise division "./".

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采纳的回答

Abderrahim. B
Abderrahim. B 2022-8-24
Ran in:
Fs=8e3; % sampling frequency
Fc=170; % cutoff frequency
alpha=1-2*pi*Fc/Fs;
nb=round(log2(1/(1-alpha))); % number of shift to the right correspending to multiplication by alpha
NbPoints=1000;
Ndec=Fs/2/1000;
Fstart=1;
i=1:Ndec*NbPoints;
freq=Fstart*10.^(i/NbPoints)
freq = 1×4000
1.0023 1.0046 1.0069 1.0093 1.0116 1.0139 1.0162 1.0186 1.0209 1.0233 1.0257 1.0280 1.0304 1.0328 1.0351 1.0375 1.0399 1.0423 1.0447 1.0471 1.0495 1.0520 1.0544 1.0568 1.0593 1.0617 1.0641 1.0666 1.0691 1.0715
H_f=(1-alpha)*cos(pi.*freq/Fs)./sqrt(1+(alpha^2)-2*alpha*cos(2*pi.*freq/Fs))
H_f = 1×4000
1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000
semilogx(freq,20*log10(abs(H_f)))

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