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Update documentation, processing of root_locus kvect keyword #989

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Apr 6, 2024
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Update documentation, processing of root_locus kvect keyword #989

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a9415a0
update documentation, processing of root_locus kvect keyword
murrayrm Apr 4, 2024
1b59bd6
fix typo identified by @bnavigator
murrayrm Apr 6, 2024
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28 changes: 15 additions & 13 deletions control/rlocus.py
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Original file line number Diff line number Diff line change
Expand Up @@ -42,15 +42,15 @@ def root_locus_map(sysdata, gains=None):
"""Compute the root locus map for an LTI system.

Calculate the root locus by finding the roots of 1 + k * G(s) where G
is a linear system with transfer function num(s)/den(s) and each k is
an element of kvect.
is a linear system and k varies over a range of gains.

Parameters
----------
sys : LTI system or list of LTI systems
Linear input/output systems (SISO only, for now).
gains : array_like, optional
Gains to use in computing plot of closed-loop poles.
Gains to use in computing plot of closed-loop poles. If not given,
gains are chosen to include the main features of the root locus map.

Returns
-------
Expand Down Expand Up @@ -98,20 +98,20 @@ def root_locus_map(sysdata, gains=None):


def root_locus_plot(
sysdata, kvect=None, grid=None, plot=None, **kwargs):
sysdata, gains=None, grid=None, plot=None, **kwargs):

"""Root locus plot.

Calculate the root locus by finding the roots of 1 + k * G(s) where G
is a linear system with transfer function num(s)/den(s) and each k is
an element of kvect.
is a linear system and k varies over a range of gains.

Parameters
----------
sysdata : PoleZeroMap or LTI object or list
Linear input/output systems (SISO only, for now).
kvect : array_like, optional
Gains to use in computing plot of closed-loop poles.
gains : array_like, optional
Gains to use in computing plot of closed-loop poles. If not given,
gains are chosen to include the main features of the root locus map.
xlim : tuple or list, optional
Set limits of x axis, normally with tuple
(see :doc:`matplotlib:api/axes_api`).
Expand Down Expand Up @@ -145,10 +145,9 @@ def root_locus_plot(
* lines[idx, 2]: loci

roots, gains : ndarray
(legacy) If the `plot` keyword is given, returns the
closed-loop root locations, arranged such that each row
corresponds to a gain in gains, and the array of gains (ame as
kvect keyword argument if provided).
(legacy) If the `plot` keyword is given, returns the closed-loop
root locations, arranged such that each row corresponds to a gain,
and the array of gains (same as `gains` keyword argument if provided).

Notes
-----
Expand All @@ -160,13 +159,16 @@ def root_locus_plot(
"""
from .pzmap import pole_zero_plot

# Legacy parameters
gains = config._process_legacy_keyword(kwargs, 'kvect', 'gains', gains)

# Set default parameters
grid = config._get_param('rlocus', 'grid', grid, _rlocus_defaults)

if isinstance(sysdata, list) and all(
[isinstance(sys, LTI) for sys in sysdata]) or \
isinstance(sysdata, LTI):
responses = root_locus_map(sysdata, gains=kvect)
responses = root_locus_map(sysdata, gains=gains)
else:
responses = sysdata

Expand Down
7 changes: 7 additions & 0 deletions control/tests/rlocus_test.py
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Expand Up @@ -180,6 +180,13 @@ def test_root_locus_plots(sys, grid, xlim, ylim, interactive):
# TODO: add tests to make sure everything "looks" OK


# Test deprecated keywords
def test_root_locus_legacy():
sys = ct.rss(2, 1, 1)
with pytest.warns(DeprecationWarning, match="'kvect' is deprecated"):
ct.root_locus_plot(sys, kvect=[0, 1, 2])


# Generate plots used in documentation
def test_root_locus_documentation(savefigs=False):
plt.figure()
Expand Down
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