Using for loop to plot multiple plots on the same graph

I am trying to plot 3 plots on the same graph , I believe the best way to do this would be a for loop. I'd like to keep the paramaters that I am changing flexible, so I would like to call them from an array. This is the code that I have so far, where 'Tau1' is a parameter that varies the function 'G_fun'. I am only getting one plot which the legend is labelling to be the last plot with Tau1 = 1e-5. How would I be get a different plot of G_fun for each value of Tau1 on the same graph? Thank you in advance for any help.

N = [1e-3,1e-4,1e-5];

for i = 1:1:3 
    Tau1 = N(i);   % the parameter to be changed
    if N(i) == 1e-3 
        figure
        hold on 
    end  % end if
    bode(G_fun);   
end
hold off
legend('Tau1 1e-3', 'Tau1 1e-4', 'Tau1 1e-5')
grid on
title('System Bode Plots')

[DGM]

What is G_fun? How is it getting the parameter Tau1?

Answer 1

[DGM]

I'm going to guess the primary issue is with your function not getting access to the changing parameter, but let's just show that it does work. There are a few things that can be improved:

% i just changed these to suit my example TF
N = [2e-1,1e-1,1e-2];

% you can just move this outside the loop to avoid the conditional
figure
hold on 
legendstrings=cell(size(N));
for i = 1:length(N) % make stuff independent of array sizes
    Tau1 = N(i);
    
    % idk what your TF is or how tau is used in it
    % this is just some garbage i made as an example
    H = tf([1 0.1 7.5*(1-Tau1)],[1 0.12 9 0 0]);
    bode(H) 
    
    % build the legends from the parameters themselves
    % instead of using literal strings that might be wrong if N changes
    legendstrings{i}=sprintf('Tau1 = %2.2e',Tau1);
end
hold off
legend(legendstrings,'location','northwest') % you can just set the location as needed
grid on
title('System Bode Plots')

[RPS19]

Thank you! This is a much better way of doing it, much more flexible which is what I needed. The problem was with my function not getting access to the variables. I had G_fun = G(a,b,c,Tau1) where G() is my actual transfer function. When I inputted G() instead of G_fun within the for loop it worked perfectly, although I don't completely understand why.

Answer 2

[William Rose]

Try putting the figure command and the hold on command outside and before the for loop.