title: Emulating MATLAB's ode15s in Python
body: <p>I am working on translating a model from MATLAB to Python. The crux of the model lies in MATLAB's ode15s. In the MATLAB execution, the ode15s has standard options:</p>
  
  <pre><code>options = odeset()
  [t P] = ode15s(@MODELfun, tspan, y0, options, params)
  </code></pre>
  
  <p>For reference, y0 is a vector (of size 98) as is MODELfun.</p>
  
  <p>My Python attempt at an equivalent is as follows: </p>
  
  <pre><code>ode15s = scipy.integrate.ode(Model.fun)
  ode15s.set_integrator('vode', method = 'bdf', order = 15)
  ode15s.set_initial_value(y0).set_f_params(params)
  dt = 1 
  while ode15s.successful() and ode15s.t &lt; duration:
       ode15s.integrate(ode15s.t+dt)
  </code></pre>
  
  <p>This though, does not seem to be working. Any suggestions, or an alternative? </p>
  
  <p>Edit: 
  After looking at the output, the result I'm getting from the Python is either no change in some elements of y0 over time, or a constant change at each step for the rest of the y0. Any experience with something like this? </p>