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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Numpy automatically casting Complex to Float","articleBody":"It's been a while since i've used this awesome work you guys did.\r\nTried some simple things today and couldn't get it to work\r\n\r\nI believe numpy got updated and messed some things up\r\n\r\nGiven the following code:\r\n```\r\nimport control as ct\r\nimport numpy as np\r\n\r\n# Define Poles and get it's coeficients\r\npoles = np.array([np.complex(-7.7, 6.4), np.complex(7.7, 6.4)]) # Expecting to get these poles when G.pole() is called\r\ncoefs = np.poly(poles)\r\n\r\n# Define the Transfer Function\r\nnum = [1]\r\nden = coefs\r\nG = ct.tf(num, den)\r\n\r\n# Get the poles\r\nG.pole()\r\n```\r\n\r\ni get these warnings:\r\n\r\n`\r\n/usr/local/lib/python3.7/dist-packages/control/xferfcn.py:957: ComplexWarning: Casting complex values to real discards the imaginary part den[j, :maxindex+1] = poly(poles[j])\r\n`\r\n`\r\n/usr/local/lib/python3.7/dist-packages/control/xferfcn.py:987: ComplexWarning: Casting complex values to real discards the imaginary part num[i, j, maxindex+1-len(numpoly):maxindex+1] = numpoly\r\narray([-10.0124922,  10.0124922])\r\n`\r\n\r\nDoing a few tests i found out that\r\n\r\n```\r\npoles = np.array([np.complex(-7.7, 6.4), np.complex(7.7, 6.4)])\r\n\r\nmaxindex = 2\r\nden = np.zeros((1, maxindex + 1), dtype=np.float)\r\nden[0, :maxindex + 1] = np.poly(poles)\r\n```\r\n`/usr/local/lib/python3.7/dist-packages/ipykernel_launcher.py:5: ComplexWarning: Casting complex values to real discards the imaginary part`\r\nwill results in the same warnings, but changing dtype to np.complex it works correctly\r\n```\r\npoles = np.array([np.complex(-7.7, 6.4), np.complex(7.7, 6.4)])\r\n\r\nmaxindex = 2\r\nden = np.zeros((1, maxindex + 1), dtype=np.complex)\r\nden[0, :maxindex + 1] = np.poly(poles)\r\nden\r\n```\r\n`array([   1.   +0.j ,    0.  -12.8j, -100.25 +0.j ])`\r\n\r\nI belive changing the num and den dtype to np.complex from xferfcn.py file should solve the issue (did not look up for similar issues/solutions though)\r\n```\r\n938        den = zeros((self.inputs, maxindex + 1), dtype=np.complex)\r\n939        num = zeros((max(1, self.outputs, self.inputs),\r\n940                     max(1, self.outputs, self.inputs),\r\n941                     maxindex + 1),\r\n942                    dtype=np.complex)\r\n```\r\n","author":{"url":"https://github.com/Bruno-SW","@type":"Person","name":"Bruno-SW"},"datePublished":"2021-02-24T19:30:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/551/python-control/issues/551"}