I am trying to plot step responses in matlab and cannot figure it out for anything, I have graphed a Bode plot for 3 different K values and now must do the same for step, but am trying to no avail, can anyone provide any suggestions?

Here is the differential equation in the time domain:

d^2y(t)/dt + (v/m)dy(t)/dt + (k/m)y(t) = (k/m)x(t)

Here is the code for my Bode plot and my attempted but failed step:

`w=logspace(-2,2,100);`

b=[1];

a=[1 2^(.5) 1];

H1=freqs(b,a,w);

b=[.09];

a=[1 (2^.5)*(.09^.5) .09];

H2=freqs(b,a,w);

b=[4];

a=[1 2*(2^.5) 4];

H3=freqs(b,a,w);

loglog(H1,w,'r-')

hold on

loglog(H2,w,'g*')

loglog(H3,w,'bo')

xlabel('Omega')

ylabel('Frequency Response')

title('Bode plot of various K values')

legend('H1, K=1','H2, K=.09','H3, K=4')

hold off

x=linspace(0,30);

eqn1=' D2y + (2^.5)*Dy + (1)*y=(1)*x';

eqn2=' D2y + (2^.5*(.09^.5))*Dy + (.09)*y=(.09)*x';

eqn3=' D2y + (2^.5*(2))*Dy + (2)*y=(2)*x';

y1=dsolve(eqn1);

y2=dsolve(eqn2);

y3=dsolve(eqn3);

z1 = eval(vectorize(y1))

z2 = eval(vectorize(y2))

z3 = eval(vectorize(y3))

http://ift.tt/1icrZlP