butterworth low pass filter in matlab

To implement a Butterworth low-pass filter in MATLAB, you can use the butter function. This function generates the coefficients of the digital Butterworth filter, which can be applied to an input signal using the filter function.

Here's the code for implementing a Butterworth low-pass filter with a cutoff frequency of 100Hz for an input signal x with a sample rate of 1000Hz:

main.m
% Define filter parameters
cutoff = 100; % Hz
order = 4;

% Compute filter coefficients
[b, a] = butter(order, cutoff / (1000/2));

% Apply filter to signal
y = filter(b, a, x);
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In this code, cutoff is the desired cutoff frequency, order is the filter order, b and a are the filter coefficients generated by the butter function, x is the input signal, and y is the output of the filtered signal.

Note that the cutoff frequency is normalized by the Nyquist frequency, which is half of the sample rate (1000/2 in this case). Also, the order parameter determines the steepness of the filter cutoff. A higher order will result in a sharper cutoff, but also a longer filter delay.