Hi Zainab,
After analyzing your code, there were several bugs found in the code as mentioned below.
The variable filter_initialized is misspelled as filter_initalized.
The function butter2sos is called but not implemented in the provided code.
The variables sos and g are not assigned values in all execution paths, leading to errors.
The Hd variable is used before being assigned in all code paths.
Here is the corrected code with the necessary fixes:
function y = fcn(u, fs)
persistent Hd;
persistent filter_initialized;
if isempty(filter_initialized)
filter_order = 5;
low_cutoff = 20;
high_cutoff = 500;
Wn = [low_cutoff high_cutoff] / (fs / 2);
[b, a] = butter(filter_order, Wn, 'bandpass');
[sos, g] = butter2sos(b, a);
g = sqrt(prod(Wn));
Hd = dsp.BiquadFilter('SOSMatrix', sos, 'ScaleValues', g);
filter_initialized = true;
end
y = step(Hd, u);
end
function [sos, g] = butter2sos(b, a)
% Implement the conversion of Butterworth filter coefficients to SOS
% and scale values here
% Example implementation:
[sos, g] = tf2sos(b, a);
end
By implementing the butter2sos function and correcting variable assignments and initialization, the errors related to undefined variables and missing assignments should be resolved. Remember to adjust the butter2sos function implementation based on the desired conversion method for Butterworth filter coefficients to second-order sections. Hope, you can share the code with your team to help you with implementation of butter2sos function or you can try yourself to learn more about coding in Matlab. The more you learn, the better you will become at it and learning comes from learning mistakes and more experiments with coding. Good luck!
