title: Is it possible to index numpy array with sympy symbols?
body: <p>Helle I want to do some summation on a numpy array like this</p>
  
  <pre><code>import numpy as np
  import sympy as sy
  import cv2
  
  i, j = sy.symbols('i j', Integer=True)
  #next read some grayscale image to create a numpy array of pixels  
  a = cv2.imread(filename)
  b = sy.summation(sy.summation(a[i][j], (i,0,1)), (j,0,1)) #double summation
  </code></pre>
  
  <p>but I'm facing with an error. is it possible to handle numpy symbols as numpy arrays'indexes? if not can you sugest me a solution?
  Thanks.</p>