title: Matlab - solving a third order differential equation
body: <pre><code>y''' + 41y'' + 360y' + 900y = 600x' + 1200x;
  y(0)= 2 ; y'(0)= 1 ; y''(0) = -0.05
  </code></pre>
  
  <p>How can I solve this equation using the ODE45 function?</p>
  
  <p>I tried this:</p>
  
  <pre><code>==&gt;
  function dydt=f(t,y)
  
  dydt = [y(2) ; y(3) ; -41*y(3)-360*y(2)- 900*y(1)]
  
  ==&gt;
  clear all;
  
  timerange=[0 1.4]; %seconds
  initialvalues=[2 1 -0.05];
  
  
  [t,y]=ode45(@dydt, timerange, initialvalues)
  
  plot(t,y(:,1));
  </code></pre>
  
  <p>But I need put the X part in the equation - I don't know how...</p>