Solving Second Order Differential Equation !

Hi, Im trying to solve and plot the solution for a second order differential equation. After some study, I made the following code:

%--------------------------------------------------

function xp = myfunc(t,x)
% x''+2*ep*w*x'+w^2*x+d*x'*abs(x')=0
w  = (2*pi)/10.8814;
ep = 0.196;
d  = -0.271;
xp   = zeros(2,1);
xp(1)= x(2);
xp(2)= -((2*ep*w)*x(2)+(w^2*x(1))+d*abs(x(2))*x(2));
end
%---------------------------------------------------

And

%-----------------------------------
clc;
tr=0:0.1:393;
initialvalues=[17.66 0];
[t,x]=ode45('myfunc',tr,initialvalues);
plot(t,x(:,1));
%----------------------------------

The expected plot is a damped sine wave. Im not able to get it.

Any advise on what Im missing here will be great.

Thanks and Regards SLS

Answer 1

[Youssef Khmou]

hi,

The damped oscillation can be obtained by changing the sign of the constant d :

 d=0.271;

Answer 2

[SmartEngineer]

Thanks.

Its a typo I didnt notice. Should have checked it.

Anyway Thank you.