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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Output calcs produce 0's at every other call","articleBody":"I've noticed that subsystems can produce outputs = 0 on every other call to a system's output function. The final result of the simulation is correct; however if you are doing something like processing quaternions in the output function, a quaternion of all zeros is invalid and an error results (without some hacky handling of that situation).\r\n\r\nIn the code below, line 1 printouts alternate between 0 and 1 rather than printing 1 at each call.\r\n\r\n```python\r\nimport numpy as np\r\nimport control as ct\r\n\r\ndef output_sys_outputs(t, x, u, params):\r\n    print(u) # alternates between zero and 1\r\n    return u\r\n\r\noutput_sys = ct.nlsys(updfcn=None, outfcn=output_sys_outputs, inputs=1, outputs=1, name=\"output_sys\")\r\n\r\ndef input_sys_outputs(t, x, u, params):\r\n    return 1\r\n\r\ninput_sys = ct.nlsys(updfcn=None, outfcn=input_sys_outputs, outputs=1, inputs=0, name=\"input_sys\")\r\n\r\n# outputs just 1's\r\ninput_sim = ct.input_output_response(input_sys, T=np.linspace(0, 1, 100))\r\n\r\nsystem = ct.interconnect(\r\n    (input_sys, output_sys),\r\n    connections=[\r\n        ['output_sys.u', 'input_sys.y']\r\n    ],\r\n    inplist=[],\r\n    outlist=['output_sys.y']\r\n)\r\n\r\ntimeseries = ct.input_output_response(system, T=np.linspace(0, 1, 100))\r\ny = timeseries.outputs\r\nprint(y) # prints all 1's\r\n```","author":{"url":"https://github.com/corbinklett","@type":"Person","name":"corbinklett"},"datePublished":"2024-06-07T16:59:04.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/1009/python-control/issues/1009"}