title: Issue understanding scipy.integrate.RK45 requirements
body: <p>I am attempting to solve a system of first order differential equations with <code>scipy.integrate.RK45()</code>. I have scripted out the model function that I am hoping to plot (displacement vs time), but <code>RK45()</code> requires that this function takes 2 arguments, namely 't' and 'y', where 't' is a scalar and 'y' is an array in my case. This is better described below:</p>
  <p><a href="https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.RK45.html" rel="nofollow noreferrer">https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.RK45.html</a></p>
  <p>My script is as follows:</p>
  <pre><code>import numpy as np
  from scipy.integrate import RK45, RK23
  
  def model(t, y):
      
      m = 2
      c = 10
      k = 1500
  
      if (t &gt;= 0 and t &lt; 0.1):
          F = 200 * t
      if (t &gt;= 0.1 and t &lt; 0.25):
          F = 20
      else:
          F = 0
      
      E_matrix = [[0, 1], [(-k / m), (-c / m)]]
      Q_matrix = [0, F / m]
  
      return E_matrix * X + Q_matrix
  
  time_step = 0.01
  t_upper = 0.5
  t_lower = 0
  
  initial_conditions = [0, 0]
  
  points_to_plot = RK45(fun=model(t, y), t0=t_lower, y0=initial_conditions, t_bound=t_upper, vectorized=True)
  </code></pre>
  <p>A picture of the system I'd like to solve is seen below:
  <a href="https://i.stack.imgur.com/G6cFB.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/G6cFB.jpg" alt="System of DEs" /></a></p>
  <p>I have found very few examples of this being used as most solutions use <code>odeint()</code>.</p>
  <p><strong>What are these two arguments (t, y) and how would I effectively incorporate them into my function?</strong></p>