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GeezerVison is showing github.com — discard zero imaginary part for sys.dcgain() by bnavigator · Pull Request #579 · python-control/python-control

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@bnavigator

@bnavigator bnavigator commented Mar 19, 2021

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Closes #578

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@coveralls

coveralls commented Mar 19, 2021 •
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Coverage Status

Coverage increased (+0.2%) to 89.14% when pulling 9a54254 on bnavigator:dcgain-real into 22b9953 on python-control:master.
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@bnavigator
bnavigator force-pushed the dcgain-real branch from f9db86a to d8bddbb Compare March 19, 2021 23:09
@bnavigator
discard zero imaginary part for sys.dcgain()
8c9e807
@bnavigator
bnavigator marked this pull request as ready for review March 19, 2021 23:10
@bnavigator
bnavigator force-pushed the dcgain-real branch from d8bddbb to 8c9e807 Compare March 19, 2021 23:10
@bnavigator
bnavigator requested a review from sawyerbfuller March 19, 2021 23:11
murrayrm
murrayrm reviewed Mar 19, 2021
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Comment thread control/tests/freqresp_test.py Resolved

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Comment thread control/tests/freqresp_test.py Resolved

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Comment thread control/tests/freqresp_test.py
np.testing.assert_equal(
sys_tf.dcgain(warn_infinite=False), complex(np.nan, np.nan))
sys_tf.dcgain(warn_infinite=False), np.nan)

@murrayrm murrayrm Mar 19, 2021

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Consider adding a test to show that dcgain() on a system with negative gain at zero frequency returns a negative number.

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@bnavigator bnavigator Mar 19, 2021

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Already exists:

python-control/control/tests/freqresp_test.py

Lines 505 to 507 in 8c9e807

# Make sure that we get the *signed* DC gain
sys_tf = -1 / (s + 1)
np.testing.assert_almost_equal(sys_tf.dcgain(), -1)

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@bnavigator
Apply review suggestions by @murrayrm: revert comment change, remove …
9a54254 
…parameter
@bnavigator bnavigator mentioned this pull request Mar 20, 2021
enhance step_info to MIMO and time series of response data #577
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@murrayrm
murrayrm merged commit 55d7e2b into python-control:master Mar 20, 2021
sawyerbfuller
sawyerbfuller reviewed Mar 20, 2021
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Comment thread control/xferfcn.py
-------
gain : ndarray
The zero-frequency gain
gain : (outputs, inputs) ndarray or scalar

@sawyerbfuller sawyerbfuller Mar 20, 2021

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gain : (noutputs, ninputs) ndarray or scalar

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sawyerbfuller
sawyerbfuller reviewed Mar 20, 2021
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Comment thread control/statesp.py
zero-frequency (or DC) gain, or, if the frequency response is
singular, the array will be filled with (inf + nanj).

gain : (outputs, inputs) ndarray or scalar

@sawyerbfuller sawyerbfuller Mar 20, 2021

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gain : (noutputs, ninputs) ndarray or scalar

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@bnavigator bnavigator mentioned this pull request Mar 20, 2021
dcgain and step_info post PR merge cleanup #582
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@murrayrm murrayrm added this to the 0.9.0 milestone Mar 20, 2021
@bnavigator
bnavigator deleted the dcgain-real branch February 18, 2024 20:30
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@murrayrm murrayrm murrayrm left review comments
@sawyerbfuller sawyerbfuller sawyerbfuller left review comments

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Successfully merging this pull request may close these issues.

sys.dcgain() should return a real value rather than a complex value (until/unless we support complex coefficients)

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4 participants

@bnavigator @coveralls @murrayrm @sawyerbfuller
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