[python-control-developers] [python-control/python-control] ace168: Change to code for ctrb and obsv (#300)

[Bill T. <no...@gi...>]

  Branch: refs/heads/master
  Home:   https://github.com/python-control/python-control
  Commit: ace1683d0a59cc5069803f87a06ceee842194558
      https://github.com/python-control/python-control/commit/ace1683d0a59cc5069803f87a06ceee842194558
  Author: Bill Tubbs <bil...@me...>
  Date:   2019-05-18 (Sat, 18 May 2019)

  Changed paths:
    M control/statefbk.py

  Log Message:
  -----------
  Change to code for ctrb and obsv (#300)

More pythonic implementation with small speedup.