title: 2d probability distribution with rbf and scipy
body: <p>I have something similar to this problem respectivly the answer of this problem: <a href="https://stackoverflow.com/questions/19237512/rbf-interpolation-linalgerror-singular-matrix">RBF interpolation: LinAlgError: singular matrix</a> 
  <a href="https://i.stack.imgur.com/QpGM6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QpGM6.png" alt="https://i.stack.imgur.com/QpGM6.png"></a></p>
  
  <p>But I want to do the probability distribution with rbf.</p>
  
  <p><strong>My code until now:</strong></p>
  
  <pre><code>from scipy.interpolate.rbf import Rbf  # radial basis functions
  import cv2
  import matplotlib.pyplot as plt
  import numpy as np
  
  x = [1, 1, 2 ,3, 4, 4, 2, 6, 7]
  y = [0, 2, 5, 6, 2, 4, 1, 5, 2]
  
  rbf_adj = Rbf(x, y, function='gaussian')
  
  plt.figure()
  
  # Plotting the original points.
  plot3 = plt.plot(x, y, 'ko', markersize=12)  # the original points.
  
  plt.show()
  </code></pre>
  
  <p>My problem is I have only coordinates of the points: x, y
  But what can i use for z and d?</p>
  
  <p><strong>This is my error message:</strong></p>
  
  <pre><code>numpy.linalg.linalg.LinAlgError: Matrix is singular.
  </code></pre>