René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"step_info problem with non stationary systems response","articleBody":"Systems with non stationary response to step input, step_info could give wrong information:\r\n\r\n```\r\nimport numpy as np              # NumPy library\r\nimport matplotlib.pyplot as plt\r\nimport control as ctrl  # Name: control Version: 0.8.4\r\n\r\n\r\nsys2 = ctrl.tf(1,[1,1,0]) \r\ntime,yout=ctrl.step_response(sys2)\r\nplt.figure()\r\nplt.plot(time,yout)\r\ninfo=ctrl.step_info(sys2)\r\n\r\n```\r\n{'RiseTime': 19.0,\r\n 'SettlingTime': 24.5,\r\n 'SettlingMin': 21.500000000169212,\r\n 'SettlingMax': 23.750000000017877,\r\n 'Overshoot': 0.0,\r\n 'Undershoot': 0.0,\r\n 'Peak': 23.750000000017877,\r\n 'PeakTime': 24.75,\r\n 'SteadyStateValue': 23.750000000017877}\r\n\r\n![Figure_16](https://user-images.githubusercontent.com/21680839/110946654-e7223100-831d-11eb-93aa-b071d825b191.png)\r\n\r\nThe step_info expected result for this system could be:\r\n\r\n tupla with fields:   \r\n \r\n RiseTime         :  nan \r\n RiseTimeInit     :  nan \r\n SettlingTime     :  nan \r\n SettlingMin      :  nan \r\n SettlingMax      :  nan \r\n Overshoot        :  nan \r\n Undershoot       :  nan \r\n Peak             :  inf \r\n PeakTime         :  inf \r\n SteadyStateValue :  nan ","author":{"url":"https://github.com/juanodecc","@type":"Person","name":"juanodecc"},"datePublished":"2021-03-12T13:32:37.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/564/python-control/issues/564"}