function [signal_filtered, Z,P] = iirFilter(N, cutoffFreq, signal, samplingFreq, filterType)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% function [Z, P] = iirFilter(N, cutoffFreq, signal, samplingFreq, filterType)
% ex.: [Z, P] =iirFilter(6, 10, x, 500, 1)
%
% Task: To create and analyze an IIR low pass filter (Butterworth ror Chebychev)
%
% Inputs:
%	-N: order of the filter
%	-cutoffFreq: below this frequency, signal is not modified and above signal is attenuated
%	-samplingFreq: sampling frequency (In Hz)
%   -signal: signal to be filter    
%	-filterType: Butterworth if equal to 1 and Chebychev if equal to 2
%
% Outputs: 
%	
%
% Author: Guillaume Gibert, guillaume.gibert@ecam.fr
% Date: 09/04/2025
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if (filterType == 1)
	[b, a] = butter(N, cutoffFreq/(samplingFreq/2));
elseif (filterType == 2)
	Rp = 10; % bandpass ripple of Rp dB
	[b, a] = cheby1(N, Rp, cutoffFreq/(samplingFreq/2));
else
	disp('Filter type is incorrect!')
	return
end

[Z, P] = zeroPole(a, b, 1);

figure;
freqz(b, a, N, samplingFreq);
title('Frequency response');
grid on;

signal_filtered = filter(b, a, signal);