How would I add titles to this subplot?

for i = 1:7 %run 7 times i is the number of loop
    [Rev, Inv] = hw5_NC_function(300, 300, 300);
    RevWeek(i) = Rev;
    t = 1:size(Inv,1);
    for kk= 1:3
    subplot(3,1,kk); plot(t,Inv(:,kk));

      hold on
      end

end

[Walter Roberson]

What would be your desired title?

[Nicholas Costa]

I need to add 3 separate x titles and 3 separate y titles and a title to the entire graph

[Walter Roberson]

It is not possible to add three separate x titles or y titles per subplot. You can add one x label per subplot, and one y label per subplot, and one title per subplot.

If you want a title over all three of the subplots, then see https://www.mathworks.com/matlabcentral/answers/100459-how-can-i-insert-a-title-over-a-group-of-subplots

Perhaps you want something like

for i = 1:7 %run 7 times i is the number of loop
    [Rev, Inv] = hw5_NC_function(300, 300, 300);
    RevWeek(i) = Rev;
    t = 1:size(Inv,1);
    for kk= 1:3
      subplot(3,1,kk); plot(t,Inv(:,kk));
      if i == 1 
        hold on
        xlabel('t');
        ylabel('Inv');
        title( sprintf('Inv(:,%d)', k) );
      end
    end
end

[Paul Huxel]

With regard to placing a title over all three of the subplots, starting in R2018b, you can use sgtitle to add a title to subplot grids:

https://www.mathworks.com/help/matlab/ref/sgtitle.html

[Walter Roberson]

Thanks for the update, Paul.