title: Level sets of a gaussian
body: <p>I would like to plot the level sets of this 2-arguments function : </p>
  
  <pre><code>def xi_gaussian_x(x,y):
          sigma = 0.8
          mu = 1.2
          return (1.0/(sigma*np.sqrt(2*np.pi)))*(np.exp(-(x-mu)**2/(2*sigma**2)))
  </code></pre>
  
  <p>where x and y are between -pi and pi. My code is the following : </p>
  
  <pre><code>plt.ion()
  xInterval = np.linspace(-np.pi,np.pi,num=1000)
  yInterval = np.linspace(-np.pi,np.pi,num=1000)
  levels_xi_gaussian_x=np.zeros((len(xInterval),len(yInterval)))
  for i in range(len(xInterval)):
          for j in range(len(yInterval)):
                levels_xi_gaussian_x[i,j]=xi_gaussian_x(xInterval[i],yInterval[j])
  plt.figure()
  c = plt.contour(xInterval,yInterval,levels_xi_gaussian_x.T,50)
  </code></pre>
  
  <p>Even if I increase the resolution of the x and y intervals, I still get regions in the -pi,pi plane which are empty : 
  <a href="https://i.stack.imgur.com/My4AU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/My4AU.png" alt="enter image description here"></a>
  How can I make all the plane be filled with vertical lines ? </p>