René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Observability Gramian for discrete-time systems","articleBody":"I noticed in the source code for the gram function that it says only continuous-time systems are supported for now:\r\n\r\nhttps://github.com/python-control/python-control/blob/85328d9d57e1148c04f1314b27c4ab0fa103d5ce/control/statefbk.py#L1122-L1127\r\n\r\nI checked and it doesn't raise an exception when you pass a discrete time system but I don't think this means it is calculating a gramian for a discrete-time system:\r\n\r\n```\r\nA = [[-0.31,  0.21], [-0.68, -0.57]]\r\nB = [[1.23], [1.42]]\r\nC = [[ 1.32, -0.55]]\r\nD = [[0.]]\r\nsysd = ct.ss(A, B, C, D, dt=1)\r\nassert sysd.isdtime()\r\nWo = ct.gram(sysd, 'o')\r\nprint(Wo)\r\n\r\narray([[ 3.24632551, -0.19876604],\r\n       [-0.19876604,  0.19212128]])\r\n```\r\n\r\nWhat would it take to get it working for discrete time systems?  Is it simply a different call to the same slycot module, sb03md, or is it more involved?\r\n\r\nSince I need it I'd be happy to try implementing it.\r\n\r\n\r\n","author":{"url":"https://github.com/billtubbs","@type":"Person","name":"billtubbs"},"datePublished":"2024-02-08T01:01:41.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/967/python-control/issues/967"}