Unrecognized function or variable 'correct_Fz'. so I can't plot correct_Fz

clc

clear

close all

%% Data Acquisition

%Import Data

data = load('Contaminated_Data'); %Fz|Cz|O2

data2 = load('HEOG');

%Data Extraction

eog_HEOG = -data2.heog_1(1,:); %HEOG artifact

eeg_Fz = data.sim1_con(1,:); %Raw at Fz

%% RLS ALGORITHM EXECUTION FOR Denoising at Fz is a easy, stable and fast convergence method suitable for online removal of EOG artifacts

% Execution for Fz electrode

% Variable Initialization

sample_no = size(eeg_Fz); % No of samples/time points

order = 3; % Order of the Adaptive Filter (User Tunable)

sigma = 0.01; % Initializing variable

lambda = 0.9999; % Forgetting Factor for RLS Algorithm (User Tunable)

H = zeros(order,1); % Initial filter Coefficients

R = sigma*eye(order,order); % Initial value for Reference combination

% RLS Algorithm for Adaptive Denoising

for n = 1:sample_no % Loop to simulate reality situation

s = eeg_Fz(1,n); % eeg @ Fz at that time point

if n>=order

j = 1; % calculation of last "order" reference vector

for i = n:-1:(n+1-order)

r(1,j) = eog_HEOG(1,i);

j = j+1;

end

% Calculation of Filter Coefficients

K = ((inv(R))*r)*(inv(lambda+r'*(inv(R))*r));

e = s - (r'*H);

H = H + (K*e);

R = inv((inv(lambda)*inv(R)) - ((inv(lambda))*(K)*((r)')*(inv(R))));

% Calculation Of RLS algorithm estimated signal

correct_Fz(1,n) = s - (r'*H);

end

end

% Fz Denoising plot

figure(2)

subplot(3,1,1) %HEOG plot

plot(eog_HEOG)

title('Horizontal EOG Artifact')

xlabel('sample number')

ylabel('HEOG mu volts')

subplot(3,1,2) %Raw at Fz plot

plot(eeg_Fz)

title('Raw EEG at Fz')

xlabel('sample number')

ylabel('EEG mu volts')

subplot(3,1,3) %denoised eeg at Fz plot

plot(correct_Fz)

title('Corrected EEG at Fz')

xlabel('sample number')

ylabel('EEG mu volts')

Answer 1

[Geoff Hayes]

@hue phan - how do you know if correct_Fz is getting intialized or updated with data? You have a condition in your for loop that will only update this variable under if

for n = 1:sample_no          % Loop to simulate reality situation
   
    s = eeg_Fz(1,n);         % eeg @ Fz at that time point
    if n>=order        

Or maybe your sample_no is invalid (empty or zero?) and so you don't even enter the for loop. I recommend that you use the MATLAB debugging tools to add a breakpoint to your code and then step through it to see if the correct_Fz is being created and updated as you expect.

(I'm assuming that it is the call to plot that is failing.)