title: NumPy ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
body: <p>I was calculating eigenvectors and eigenvalues of a matrix in NumPy and just wanted to check the results via an <code>assert</code> statement. This would throw a ValueError that I don't quite understand, since printing those comparisons works just fine. Any tips how I could get this <code>assert</code> statement working?</p>
  <pre><code>import numpy as np
  A = np.array([[3,5,0], [5,7,12], [0,12,5]])
  eig_val, eig_vec = np.linalg.eig(A)
  print('eigenvalue:', eig_val)
  print('eigenvector:', eig_vec)
  
  for col in range(A.shape[0]):
      assert (A.dot(eig_vec[:,col])) == (eig_val[col] * eig_vec[:,col])
  </code></pre>