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Merged
slivingston merged 4 commits into from
Dec 11, 2024
Merged

fix issue with multiplying MIMO LTI system by scalar #1078

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9acbfbb
fix issue with multiplying MIMO LTI system by scalar
murrayrm Dec 7, 2024
0b9be7a
fix misprint
slivingston Dec 11, 2024
f514f7c
fix misprint
slivingston Dec 11, 2024
3165881
fix misprint
slivingston Dec 11, 2024
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fix issue with multiplying MIMO LTI system by scalar
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@murrayrm
murrayrm committed Dec 7, 2024
commit 9acbfbbbf3b4e2c9e8453c0cc18d21df88d6230b
15 changes: 13 additions & 2 deletions control/frdata.py
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Original file line number Diff line number Diff line change
Expand Up @@ -261,14 +261,20 @@ def __init__(self, *args, **kwargs):

# create interpolation functions
if smooth:
# Set the order of the fit
if self.omega.size < 2:
raise ValueError("can't smooth with only 1 frequency")
degree = 3 if self.omega.size > 3 else self.omega.size - 1

self.ifunc = empty((self.fresp.shape[0], self.fresp.shape[1]),
dtype=tuple)
for i in range(self.fresp.shape[0]):
for j in range(self.fresp.shape[1]):
self.ifunc[i, j], u = splprep(
u=self.omega, x=[real(self.fresp[i, j, :]),
imag(self.fresp[i, j, :])],
w=1.0/(absolute(self.fresp[i, j, :]) + 0.001), s=0.0)
w=1.0/(absolute(self.fresp[i, j, :]) + 0.001),
s=0.0, k=degree)
else:
self.ifunc = None

Expand Down Expand Up @@ -392,7 +398,12 @@ def __add__(self, other):

# Convert the second argument to a frequency response function.
# or re-base the frd to the current omega (if needed)
other = _convert_to_frd(other, omega=self.omega)
if isinstance(other, (int, float, complex, np.number)):
other = _convert_to_frd(
other, omega=self.omega,
inputs=self.ninputs, outputs=self.noutputs)
else:
other = _convert_to_frd(other, omega=self.omega)

# Check that the input-output sizes are consistent.
if self.ninputs != other.ninputs:
Expand Down
18 changes: 18 additions & 0 deletions control/tests/lti_test.py
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Expand Up @@ -350,3 +350,21 @@ def test_subsys_indexing(fcn, outdx, inpdx, key):
np.testing.assert_almost_equal(
subsys_fcn.frequency_response(omega).response,
subsys_chk.frequency_response(omega).response)


@slycotonly
@pytest.mark.parametrize("op", [
'__mul__', '__rmul__', '__add__', '__radd__', '__sub__', '__rsub__'])
@pytest.mark.parametrize("fcn", [ct.ss, ct.tf, ct.frd])
def test_scalar_algebra(op, fcn):
sys_ss = ct.rss(4, 2, 2)
match fcn:
case ct.ss:
sys = sys_ss
case ct.tf:
sys = ct.tf(sys_ss)
case ct.frd:
sys = ct.frd(sys_ss, [0.1, 1, 10])

scaled = getattr(sys, op)(2)
np.testing.assert_almost_equal(getattr(sys(1j), op)(2), scaled(1j))
17 changes: 8 additions & 9 deletions control/xferfcn.py
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Expand Up @@ -634,11 +634,11 @@ def __mul__(self, other):
from .statesp import StateSpace

# Convert the second argument to a transfer function.
if isinstance(other, StateSpace):
if isinstance(other, (StateSpace, np.ndarray)):
other = _convert_to_transfer_function(other)
elif isinstance(other, (int, float, complex, np.number, np.ndarray)):
other = _convert_to_transfer_function(other, inputs=self.ninputs,
outputs=self.noutputs)
elif isinstance(other, (int, float, complex, np.number)):
# Multiply by a scaled identify matrix (transfer function)
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other = _convert_to_transfer_function(np.eye(self.ninputs) * other)
if not isinstance(other, TransferFunction):
return NotImplemented

Expand Down Expand Up @@ -681,8 +681,8 @@ def __rmul__(self, other):

# Convert the second argument to a transfer function.
if isinstance(other, (int, float, complex, np.number)):
other = _convert_to_transfer_function(other, inputs=self.ninputs,
outputs=self.ninputs)
# Multiply by a scaled identify matrix (transfer function)
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other = _convert_to_transfer_function(np.eye(self.noutputs) * other)
else:
other = _convert_to_transfer_function(other)

Expand Down Expand Up @@ -723,9 +723,8 @@ def __truediv__(self, other):
"""Divide two LTI objects."""

if isinstance(other, (int, float, complex, np.number)):
other = _convert_to_transfer_function(
other, inputs=self.ninputs,
outputs=self.ninputs)
# Multiply by a scaled identify matrix (transfer function)
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other = _convert_to_transfer_function(np.eye(self.ninputs) * other)
else:
other = _convert_to_transfer_function(other)

Expand Down