title: Index is out of bounds for axis 0 with size 100
body: <p>I have a function where I am populating a 100x100 2D array with values by iterating over a for loop. I need to store values in the [i][i], [i][i-1], and [i][i+1] positions.Here is what i have so far:</p>
  
  <pre><code>    Delta = 1/100
      N = 100 
      Matrix = np.zeros(N,N), int)
  
      for i in range(N):
         Matrix[i][i] = ((2*D)/pow(Delta,2) + SigmaA)
         Matrix[i][i-1] = -(D/pow(Delta,2))
         Matrix[i][i+1] = -(D/pow(Delta,2))
  </code></pre>