clear all;
close all;
clc;

load('eegData');
samplingRate = 500;
filterOrder = 2;
lowCutoff = 0.1;
highCutoff = 30;
amountOfDataToPlot = 500;

% get some data to plot from before the filter
preFilterData = eegData(1,1:amountOfDataToPlot);
% demean the data for comparison with the filtered data
preFilterData = preFilterData - mean(preFilterData);

% define Butterworth filter
[b,a] = butter(filterOrder,[lowCutoff highCutoff]/(samplingRate/2));

% filter data one channel at a time
for channelCounter = 1:size(eegData,1) 
    eegData(channelCounter,:) = filtfilt(b,a,double(eegData(channelCounter,:)));  
end

% get some data to plot post filter
postFilterData = eegData(1,1:amountOfDataToPlot);

% plot some stuff
plot([1:1:amountOfDataToPlot],preFilterData,'linewidth',3);
hold on;
plot([1:1:amountOfDataToPlot],postFilterData,'linewidth',3);
hold off;
title('Pre versus Post Filter Data');