MATLAB: I wanted the slope with respect to time frame

slopetime series

I wanted to calculate slope of channel 1 to 15 with respect to the time frame. The values in the tables are HbO values which should be Y axis and X axis should be time time frame which in this case is 1510.
I have attached my data file as well.
How do i calculate the slope of channels 1 to 15 indivijually and place the values in a different table and perhaps even plot to visually see it????
Something similar to the url i have posted above.
Thank you

Best Answer

First, negative values for haemoglobin or oxyhaemoglobin do not make sense physiologically.
I have no idea what you want to do, so start with: 
D = load('HbO_Good_channels.mat');
HbO = D.HbO_good_channel;
Ts = 35/size(HbO,1);                                                    % Create A Sampling Interval, Since None Are Provided
T = linspace(0, size(HbO,1), size(HbO,1))*Ts;                           % Time Vector
lgdc = sprintfc('Ch %2d', 1:size(HbO,2));                               % Legend String Cell Array (Channels)
figure
plot(T, HbO)
grid
xlabel('Time')
ylabel('HbO')
legend(lgdc, 'Location','eastoutside')
for k = 1:size(HbO,2)
    cfs(k,:) = polyfit(T(:), HbO(:,k), 3);                              % Coefficient Vectors: ‘polyfit’
end
figure
hold all
for k = 1:size(HbO,2)
    pf(:,k) = polyval(cfs(k,:), T(:));                                  % Evaluate Fitted Polynomials
    plot(T, pf(:,k))
end
hold off
grid
xlabel('Time')
ylabel('Regression Fit')
legend(lgdc)
Experiment to get the resultl you want.
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