title: solution of differential equation takes huge time
body: <p>Before  posting of actual code, let me show you that my computer's processor's and memory information is good:</p>
  
  <p><a href="https://i.stack.imgur.com/jnW4w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jnW4w.png" alt="enter image description here"></a></p>
  
  <p>Yesterday I have posted  about Lorenz equation(classical equation from chaos theory), where one of  great guy helped me and show  solution, here it is:</p>
  
  <pre><code>function f=lorenz(t,x,a,b,c)
          % solve differential equation like this
          %dx/dt=a*(y-x)
          %dy/dt=-x*z+b*x-y
          %dz/dt=xy-c*z/3
          f=zeros(3,1);% preallocate result
          f(1)=a*(x(2)-x(1));
          f(2)=-x(1)*x(3)+b*x(1)-x(2);
          f(3)=x(1)*x(2)-c*x(3)/3;
          end
  </code></pre>
  
  <p>and test program (script):</p>
  
  <pre><code>% test program
  x0=[-2 -3.5 21];% initial  point
  a=input(' enter first coefficient : ');
  b=input(' enter second coefficient: ');
  c=input(' enter third coefficient : ');
  [t,x] = ode45(@(t,x) lorenz(t,x,a,b,c),[0 10],x0);
  plot(t,x(:,1),'r'); 
  title(' solution of x part');
  grid on
  </code></pre>
  
  <p>But after running those lines</p>
  
  <pre><code>test_program
   enter first coefficient : 10
   enter second coefficient: 28
   enter third coefficient : -8
  </code></pre>
  
  <p>it is still running,  he said that  on his personal computer, it takes  2 second, so it is really  strange  what happens? Why it is not compiling on my PC? Even  as you saw it  My laptop has good parameters, please help me - even now it is running so I should cancel  using ctrl-c.</p>