title: How does Simulink implement the Runge-Kutta Solver?
body: <p>I have a question on the same topic in math.stackexchange.com: <a href="https://math.stackexchange.com/questions/664422/how-does-matlab-simulink-get-such-accurate-ode-solution-results">https://math.stackexchange.com/questions/664422/how-does-matlab-simulink-get-such-accurate-ode-solution-results</a>, and it remains open.</p>
  
  <p>I am looking to understand how Simulink's accuracy of solving ODEs with purportedly the fourth  order Runge-Kutta solver (ODE4) far exceeds any implementation I have developed so far. Either I have incorrectly implemented the algorithm or Simulink is doing extra work behind-the-scenes to increase accuracy. I have asked on the math stack exchange site about potential mathematical methods, I ask here about computer science methods of achieving increased accuracy.</p>
  
  <p>My interest comes from a need to understand model stability using different solution methods, and not knowing what Simulink is doing to get accuracy means having less idea of its potential stability in certain situations.</p>