Legend inside a loop

Hi,

I have made a for loop that plots 20 sets of values against time. Now I want to create a different legend name for all the 20 plots. In the code I calculate dampening co-efficient called zeta. I want the legend to say x(t) for zeta = (value). This is the code I have. I went through the forum and i understand that I have to use displayname. I am not sure how it works. Any help is greately appreciated.

% given

k = 2000;
m = 150;
x0 = 0;
v0 = 0.010;
c = (50:50:1000);
wn = sqrt(k/m);
t = (0:0.005:5);
xt = zeros(numel(c),numel(t));
zeta = zeros(1,numel(c));
wd = zeros(1,numel(c));
phi = zeros(1,numel(c));
A = zeros(1,numel(c));

for i = 1:numel(c)
   
    zeta(i) = c(i)/(2*sqrt(m*k));
    wd(i) = wn*(sqrt(1-zeta(i)^2));
    phi(i) = atan((wd(i)*x0)/(v0+(zeta(i)*wn*x0)));
    A(i) = (1/wd(i))*(sqrt((v0+zeta(i)*x0*wn)^2+(x0*wd(i))^2));
    
    for j = 1:numel(t)
       
       xt(i,j) = (A(i)*sin(wd(i)*t(j)+phi(i))*exp(-zeta(i)*wn*t(j)));
        
    end
    
end
for k = 1:numel(c)

    figure
%     set(gcf, 'WindowState', 'maximized');
    plot (t,xt(k,:))
    title ('Assignment 2 Problem 1.61')
    xlabel('Time')
    ylabel('x(t)')
    legend(' problem is here ')

end

Answer 1

[Mario Malic]

Something like this should work.

for k=1:1:length(c)
    legendstr{1,k} = sprintf('zeta = %f', zetavalue); %legendstr changes size
    legend(legendstr)
end

[Tejas Appaji]

will this peice of code go in the existing loop for plot or is it a seperate loop ?

[Mario Malic]

In your loop with variable k, you're plotting each curve, and if you add this, it creates a legend cell that contains names of curves as they increase with each loop.

[Tejas Appaji]

Thank you so much. That really helps.