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jerabaul29

opened on Jun 12, 2020

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I think the doc about the return type of the lqr function looks inconsistent:

https://python-control.readthedocs.io/en/0.8.1/generated/control.lqr.html

states that K is a 2-d array. But it looks a lot like a matrix actually :)

>>> K, _, _ = control.lqr(np.array([1]), np.array([1]), np.array([1]), np.array([1]))
>>> K
matrix([[2.41421356]])

This is Python 3.6.9, control 0.8.3, Ubuntu 18.04 defaults.

This leads to possibly subtle bugs:

https://stackoverflow.com/questions/62342225/how-to-squeeze-when-numpy-squeeze-does-not-seem-to-squeeze?

Do you think it may be a good idea to 1) update the doc 2) maybe change from matrix to array output altogether? :)

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1. murrayrm commented on Jun 12, 2020

   

   murrayrm

   on Jun 12, 2020

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   The plan is to shift away from the use of the np.matrix class at a future point. This functionality is already in place through the use of the use_numpy_matrix function. In version 0.8.3, the np.matrix class is still used for backward compatibility, but you can switch to using arrays through the function call

   control.use_numpy_matrix(False)
   

   When we release version 0.9.0, we will switch to have np.ndarray be the default class for all matrices in python-control.

   I'll leave this issue open for a bit because I think we generally need to update the documentation to reflect that fact that the return type for functions depends on how you have configured python-control. I've been collecting up documentation updates, so will include those changes in that PR.

   Reacted by JR
2. murrayrm

   added

   documentation

   on Jun 12, 2020
3. murrayrm

   self-assigned this

   on Jun 12, 2020
4. murrayrm

   added this to the 0.8.4 milestone on Jun 12, 2020
5. murrayrm

   added a commit that references this issue on Dec 22, 2020

   update lqr() return type documentation (addresses python-control#418)

   3e6347f
6. bnavigator

   linked a pull request that will close this issueDocumentation update #476on Dec 22, 2020
7. murrayrm

   closed this as completedin #476on Dec 24, 2020
8. murrayrm

   added a commit that references this issue on Dec 24, 2020

   Documentation update (#476)

   120a926

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