>>> a = np.stack((np.eye(3),)*4, axis=0)
>>> ai = np.linalg.inv(a)
>>> assert (a == ai).all()
>>> api = np.linalg.pinv(a)
Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    np.linalg.pinv(a)
  File "C:\Program Files\Python 3.5\lib\site-packages\numpy\linalg\linalg.py", line 1668, in pinv
    if s[i] > cutoff:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()