MATLAB: Writing differential equation for plot

second order differential equation

Can anyone help me how to write differential below equation for plot

d2x/dt2 = -sign(x + dx/dt)

I tried in below way and it is failing

ode = diff(x,t,2) == -sign(x + diff(x,t));

Try this

syms x(t)
d1x = diff(x);
d2x = diff(x,2);
ode = d2x == -sign(x + d1x);
cond = [x(0)==1 d1x(0)==0]
sol = dsolve(ode, cond)

This requires the Symbolic Math toolbox.

I can!

Try this:

syms x(t);
Dx = diff(x);
Dx2 = diff(x,2);
x(t) = dsolve(Dx2+(5*Dx)+(6*x)==100,x(0)==0,Dx(0)==0)
figure(1)
fplot(x, [0 10])
axis([xlim    0  17])
grid

Use fplot if you have R2016a or later, ezplot otherwise.