>> sol2=dsolve('D2x=-2*Dx-1','x(0)=1,Dx(0)=1','a');
>> sol3=dsolve('D2x=-3*Dx-1','x(0)=1,Dx(0)=1','a');
>> sol1=dsolve('D2x=-Dx-1','x(0)=1,Dx(0)=1','t');
>> sol2=dsolve('D2x=-2*Dx-1','x(0)=1,Dx(0)=1','t');
>> sol3=dsolve('D2x=-3*Dx-1','x(0)=1,Dx(0)=1','t');
>> t=linspace(0,20*pi);
>> y1=eval(sol1);
>> y2=eval(sol2);
>> y3=eval(sol3);
>> plot(t,y1,t,y2,t,y3)
大致就是這樣,自己調整Dx的系數,也就是阻尼比吧,這裏取得是1,2,3可能不太合理,但是程序的框架就這樣