8000 Allow division by scalar for StateSpace & InputOutputSystem · python-control/python-control@f81b6d2 · GitHub
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Allow division by scalar for StateSpace & InputOutputSystem
Attempt division by any non-LTI and non-NameIOSystem by translating G / k to G * (1/k). Division of StateSpace by TransferFunction, etc., unchanged.
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4 files changed

+33
-14
lines changed

4 files changed

+33
-14
lines changed

‎control/iosys.py‎

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@@ -346,6 +346,17 @@ def __neg__(sys):
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# Return the newly created system
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return newsys
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def __truediv__(sys2, sys1):
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"""Multiply two input/output systems (series interconnection)"""
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# Note: order of arguments is flipped so that self = sys2,
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# corresponding to the ordering convention of sys2 * sys1
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if not isinstance(sys1, (LTI, NamedIOSystem)):
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return sys2 * (1/sys1)
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else:
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return NotImplemented
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# Update parameters used for _rhs, _out (used by subclasses)
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def _update_params(self, params, warning=False):
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if warning:
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‎control/statesp.py‎

Lines changed: 8 additions & 11 deletions
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@@ -64,7 +64,7 @@
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from .frdata import FrequencyResponseData
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from .lti import LTI, _process_frequency_response
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from .namedio import common_timebase, isdtime, _process_namedio_keywords, \
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_process_dt_keyword
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_process_dt_keyword, NamedIOSystem
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from . import config
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from copy import deepcopy
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@@ -794,17 +794,14 @@ def __rmul__(self, other):
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pass
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raise TypeError("can't interconnect systems")
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# TODO: __div__ and __rdiv__ are not written yet.
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def __div__(self, other):
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"""Divide two LTI systems."""
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raise NotImplementedError("StateSpace.__div__ is not implemented yet.")
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def __rdiv__(self, other):
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"""Right divide two LTI systems."""
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# TODO: general __truediv__, and __rtruediv__; requires descriptor system support
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def __truediv__(self, other):
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"""Divide a StateSpace object; only division by scalars is supported"""
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if not isinstance(other, (LTI, NamedIOSystem)):
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return self * (1/other)
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else:
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return NotImplemented
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raise NotImplementedError(
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"StateSpace.__rdiv__ is not implemented yet.")
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def __call__(self, x, squeeze=None, warn_infinite=True):
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"""Evaluate system's transfer function at complex frequency.

‎control/tests/statesp_test.py‎

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@@ -333,6 +333,17 @@ def test_multiply_ss(self, sys222, sys322):
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np.testing.assert_array_almost_equal(sys.C, C)
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np.testing.assert_array_almost_equal(sys.D, D)
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@pytest.mark.parametrize("k", [2, -3.141, np.float32(2.718), np.array([[4.321], [5.678]])])
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def test_truediv_ss_scalar(self, sys322, k):
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"""Divide SS by scalar."""
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sys = sys322 / k
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syscheck = sys322 * (1/k)
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np.testing.assert_array_almost_equal(sys.A, syscheck.A)
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np.testing.assert_array_almost_equal(sys.B, syscheck.B)
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np.testing.assert_array_almost_equal(sys.C, syscheck.C)
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np.testing.assert_array_almost_equal(sys.D, syscheck.D)
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@pytest.mark.parametrize("omega, resp",
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[(1.,
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np.array([[ 4.37636761e-05-0.01522976j,

‎control/tests/type_conversion_test.py‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -88,11 +88,11 @@ def sys_dict():
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('mul', 'flt', ['ss', 'tf', 'frd', 'lio', 'ios', 'arr', 'flt']),
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# op left ss tf frd lio ios arr flt
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('truediv', 'ss', ['xs', 'tf', 'frd', 'xio', 'xos', 'xs', 'xs' ]),
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('truediv', 'ss', ['xs', 'tf', 'frd', 'xio', 'xos', 'ss', 'ss' ]),
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('truediv', 'tf', ['tf', 'tf', 'xrd', 'tf', 'xos', 'tf', 'tf' ]),
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('truediv', 'frd', ['frd', 'frd', 'frd', 'frd', 'E', 'frd', 'frd']),
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('truediv', 'lio', ['xio', 'tf', 'frd', 'xio', 'xio', 'xio', 'xio']),
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('truediv', 'ios', ['xos', 'xos', 'E', 'xos', 'xos' 'xos', 'xos']),
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('truediv', 'lio', ['xio', 'tf', 'frd', 'xio', 'xio', 'lio', 'lio']),
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('truediv', 'ios', ['xos', 'xos', 'E', 'xos', 'xos', 'ios', 'ios']),
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('truediv', 'arr', ['xs', 'tf', 'frd', 'xio', 'xos', 'arr', 'arr']),
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('truediv', 'flt', ['xs', 'tf', 'frd', 'xio', 'xos', 'arr', 'flt'])]
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