René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"DC gain evaluation of State-space objects","articleBody":"Currently (see [1]) if a state space system has eigenvalues at 0, it will return a scalar NaN for DC gain:\r\n```python\r\n        except LinAlgError:\r\n            # zero eigenvalue: singular matrix\r\n            return np.nan\r\n```\r\nThe shape of the return is addressed in #126.\r\n\r\nIt may be possible to do better here: one relatively expensive way would be to `minreal` each input output pair and evaluate the DC gain.  This would allow finite and non-finite entries in the returned matrix, rather than all NaNs.  I'm not sure how to decide on +inf or -inf instead of NaN: in `C*inv(-A)*B`, if we find some sort of inverse of A that has infs (this is not hard using, e.g., singular value decomposition), one could still potentially add or subtract infs when multiplying by C and B, so getting NaNs.\r\n\r\n[1] https://github.com/python-control/python-control/blob/32f13bcdf32fb7d5513a5a06ba0ca3296decdf4d/control/statesp.py#L617-L619","author":{"url":"https://github.com/roryyorke","@type":"Person","name":"roryyorke"},"datePublished":"2017-01-04T18:49:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/128/python-control/issues/128"}