plotting in a for loop

Basically i am trying to get all the iterations of the step response for all values in the zeta matrix to be placed on to the same graph using a for loop. for some reason i think it is adding them up and putting them in the same line.

%%

zeta= [-.02,0,.05,.2,1,2];

omegan=2*pi;

num=[omegan^2];

for i=numel(zeta)

den{i}=[1 2*zeta(i)*omegan omegan^2];

sys(i)=tf(num,den{i});

tfinal=4;

numpts=201;

time=0:tfinal/(numpts-1):tfinal;

y{i}=step(sys(i),time);

plot(time,y{i})

hold on

plot([0 tfinal], [1 1], 'k-')

xlabel ('t (sec)')

ylabel ('y(t) (m)')

title ('Step Response')

end

Answer 1

[Mathieu NOE]

hi

see modified code

zeta= [-.02,0,.05,.2,1,2];
omegan=2*pi;
num=[omegan^2];

tfinal=4;
numpts=201;
time=0:tfinal/(numpts-1):tfinal;

y_plot = zeros(numpts , numel(zeta));

for i= 1:numel(zeta)
    den{i}=[1 2*zeta(i)*omegan omegan^2];
    sys(i)=tf(num,den{i});
    [y,t]=step(sys(i),time);
    y_plot(:,i) = y; 
    mylegend{i+1} = ([' zeta = ' num2str(zeta(i)) ]);
    
end

mylegend{1} = (' target ');

    plot([0 tfinal], [1 1], 'k-',time,y_plot)
    legend(mylegend');
    xlabel ('t (sec)')
    ylabel ('y(t) (m)')
    title ('Step Response')