create a symmetric filter in matlab

To create a symmetric filter in MATLAB, we can use the fir1 function. By default, this function will create a linear-phase, symmetric filter.

Here's an example code snippet to create a low-pass filter with a cutoff frequency of 0.2 Hz and length of 101:

main.m
fs = 1000;           % Sampling frequency
fc = 0.2;            % Cutoff frequency
N = 101;             % Filter order

% Create symmetric low-pass filter
b = fir1(N-1, fc/(fs/2), 'low', 'symmetric');

% Visualize filter response
freqz(b, 1, 1024, fs);
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In this code, fs is the sampling frequency, fc is the cutoff frequency, and N is the length of the filter kernel. The fir1 function creates a low-pass filter of length N-1 with a cutoff frequency of fc normalized to the Nyquist frequency (fs/2). The 'low' parameter specifies that we want a low-pass filter, and 'symmetric' specifies that we want a symmetric filter.

Finally, we use the freqz function to visualize the frequency response of the filter.