title: Plot a lagrange polynomial from a set of points PYTHON
body: <p>I need to draw a curve passing through the points (0,0) , (20,10) , (0,50). As there two points with the same x coordinate, I decided to parametrize x and y with a parameter t and since I need the equation of this polynomial (of the curve) I decided tot use Lagrange. 
  Well, the plot is really weird, it prints the points, but there is no curve: <a href="https://i.stack.imgur.com/ZO6tp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZO6tp.png" alt="weird plot"></a></p>
  
  <pre><code>x_parabola = np.array([0, 20, 0]) # array for x
  y_parabola = np.array([0, 10, 50]) # array for y
  plt.figure()
  u = plt.plot(x_parabola,y_parabola,'ro') # plot the points
  t = np.linspace(0, 1, len(x_parabola)) # parameter t to parametrize x and y
  pxLagrange = scipy.interpolate.lagrange(t, x) # X(T)
  pyLagrange = scipy.interpolate.lagrange(t, y) # Y(T)
  n = 100
  ts = np.linspace(t[0],t[-1],n)
  xLagrange = pxLagrange(ts) # lagrange x coordinates
  yLagrange = pyLagrange(ts) # lagrange y coordinates
  plt.plot(xLagrange, yLagrange,'b-',label = "Polynomial")
  </code></pre>
  
  <p>Please, could you show me what is wrong with the code? Thanks in advance!</p>