title: Plotting direction field in python
body: <p>I want to plot direction field for a simple equation:  </p>
  
  <pre><code>y'  = 3 − 2y
  </code></pre>
  
  <p>I have found similar Matlab problem <a href="http://www.math.tamu.edu/~efendiev/math442_spring04/matlabode.pdf" rel="nofollow">here</a> (1.3). But I do not know how to rewrite it to python. My last try is:  </p>
  
  <pre><code>from matplotlib.pyplot import cm
  import matplotlib.pyplot as plt
  import numpy as np
  
  nx, ny = .3, .3
  x = np.arange(-3, 3, nx)
  y = np.arange(-2, 2, ny)
  X, Y = np.meshgrid(x, y)
  
  dy = X + np.sin(Y)
  dx = np.ones((10,10))
  
  plot2 = plt.figure()
  plt.quiver(X, Y, dx, dy, 
             color='Teal', 
             headlength=7)
  
  plt.title('Quiver Plot, Single Colour')
  plt.show(plot2)
  </code></pre>
  
  <p>But I'm getting error:</p>
  
  <pre><code>builtins.ValueError: operands could not be broadcast together with shapes (100,) (280,) 
  </code></pre>
  
  <p>I though it will be very simple, but after few hours of searching how to plot a simple direction field, I am quite depressed.</p>