title: Solve_vbp with boundary conditions and arrays
body: <p>I try to solve DE with boundary conditions, but every time get this error. I edited my code with notes, that i getted, but a still have an error.
  I understand that it's an error because I cant give functions for <code>solve_bvp</code> as a vector <code>f1, f2 = y</code>, but I dont know another way.
  <br />In variables:
  <br />u1,u2 = const
  <br />x1, x2, x22 = array
  <br />f1, f2 = functions
  <br />I have 20 point in DE and 20 values in arrays. I dont understand :c
  <br />Code:</p>
  <pre><code>t_eval = np.array([0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 105, 112, 119, 126, 133, 140]) 
  u2=0.2
  u1=1.2
  x1=np.array([1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10])
  x2=np.array([1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10])
  x22=np.array([1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10])
  
  def f1f2_model(t, y):
  a1 = np.interp(t_eval, x1, f1[1])
  a2 = np.interp(t_eval, x2, f2[1])
  b1 = np.interp(t_eval, x1, f1[1])
  b2 = np.interp(t_eval, x1, f2[1])
  df1_dt = u1 * a1 - u1 * a2
  df2_dt = u1 * b1 -u1 *b2-u2*f2 + 2*(x2-x22)
  return np.vstack((u1 * a1 - u1 * a2), (u1 * b1 -u1 *b2-u2*f2[1] + 2*(x2-x22)))
  
  def bc(f1_T, f2_T):
      return np.array([f1_T[0], f2_T[0]])
  
  T=140
  n=20
  x = np.linspace(0, T, n)
  y = np.array([x, np.full_like(x, 673), np.linspace(800, 200, n)])
  
  sol = spi.solve_bvp(f1f2_model, bc, x, y)
    
  print(sol.y)
  </code></pre>
  <p>error still about &quot;too many values&quot;</p>
  <pre><code>ValueError                                Traceback (most recent call last)
  &lt;ipython-input-4-d9d4806ecb60&gt; in &lt;module&gt;
        7 #Решаем через solve_bvp
        8 #sol = spi.solve_bvp(f1f2_model, bc, x, y)
  ----&gt; 9 sol = spi.solve_bvp(f1f2_model(t, y), bc, t, y)
       10 
       11 t = np.linspace(0, T, 20)
  
  &lt;ipython-input-2-019ad077bd9c&gt; in f1f2_model(t, y)
       10 def f1f2_model(t, y):
       11 
  ---&gt; 12     f1, f2 = y
       13     a1 = np.interp(t_eval, x1, f1[1])
       14     a2 = np.interp(t_eval, x2, f2[1])
  
  ValueError: too many values to unpack (expected 2)
  </code></pre>