fft Invalid expression in plot
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Alia Hicks
el 28 de Jul. de 2020
Respondida: Alia Hicks
el 28 de Jul. de 2020
I'm recieving error "Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters." at the second from last line "plot(t,f,); %amp vs time"
dt = .001;
t = 0:dt:1;
f = data_output;
%%Compute the Fast Fourier Transform FFT
n = length(t);
fhat = fft(f,n); % Compute the fast Fourier transform
PSD = fhat.*conj(fhat)/n; % Power spectrum (power per freq)
freq = 1/(dt*n)*(0:n); % Create x-axis of frequencies in Hz
L = 1:floor(n/2); % Only plot the first half of freqs
%%Use the PSD to filter out noise
indices = PSD>100; % Find all freqs with large power
PSDclean = PSD.*indices; % Zero out all others
fhat = indices.*fhat; % Zero out small Fourier coeffs. in Y
ffilt = ifft(fhat); % Inverse FFT for filtered time signal
%%PLOTS
plot(t,f,); %amp vs time
plot(f,fft); % mag vs freq
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