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Dec 29, 2020
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skip impulse sampling for old scipy #482

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59 changes: 33 additions & 26 deletions control/tests/timeresp_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,12 @@
# specific unit tests will do that.

import unittest
from distutils.version import StrictVersion

import numpy as np
import pytest
import scipy as sp

from control.timeresp import *
from control.timeresp import _ideal_tfinal_and_dt, _default_time_vector
from control.statesp import *
Expand All @@ -29,11 +34,11 @@ def setUp(self):
# Create some transfer functions
self.siso_tf1 = TransferFunction([1], [1, 2, 1])
self.siso_tf2 = _convert_to_transfer_function(self.siso_ss1)

# tests for pole cancellation
self.pole_cancellation = TransferFunction([1.067e+05, 5.791e+04],
self.pole_cancellation = TransferFunction([1.067e+05, 5.791e+04],
[10.67, 1.067e+05, 5.791e+04])
self.no_pole_cancellation = TransferFunction([1.881e+06],
self.no_pole_cancellation = TransferFunction([1.881e+06],
[188.1, 1.881e+06])

# Create MIMO system, contains ``siso_ss1`` twice
Expand Down Expand Up @@ -177,8 +182,8 @@ def test_step_info(self):
# https://github.com/python-control/python-control/issues/440
step_info_no_cancellation = step_info(self.no_pole_cancellation)
step_info_cancellation = step_info(self.pole_cancellation)
for key in step_info_no_cancellation:
np.testing.assert_allclose(step_info_no_cancellation[key],
for key in step_info_no_cancellation:
np.testing.assert_allclose(step_info_no_cancellation[key],
step_info_cancellation[key], rtol=1e-4)

def test_impulse_response(self):
Expand Down Expand Up @@ -218,6 +223,8 @@ def test_impulse_response(self):
np.testing.assert_array_almost_equal(
yy, np.vstack((youttrue, np.zeros_like(youttrue))), decimal=4)

@pytest.mark.skipif(StrictVersion(sp.__version__) < "1.3.0",
reason="requires SciPy 1.3.0 or greater")
def test_discrete_time_impulse(self):
# discrete time impulse sampled version should match cont time
dt = 0.1
Expand All @@ -226,7 +233,7 @@ def test_discrete_time_impulse(self):
sysdt = sys.sample(dt, 'impulse')
np.testing.assert_array_almost_equal(impulse_response(sys, t)[1],
impulse_response(sysdt, t)[1])

def test_initial_response(self):
# Test SISO system
sys = self.siso_ss1
Expand Down Expand Up @@ -363,7 +370,7 @@ def test_step_robustness(self):
"Unit test: https://github.com/python-control/python-control/issues/240"
# Create 2 input, 2 output system
num = [ [[0], [1]], [[1], [0]] ]

den1 = [ [[1], [1,1]], [[1,4], [1]] ]
sys1 = TransferFunction(num, den1)

Expand All @@ -381,47 +388,47 @@ def test_auto_generated_time_vector(self):
ratio = 9.21034*p # taken from code
ratio2 = 25*p
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5]))[0],
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5]))[0],
(ratio/p))
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5]).sample(.1))[0],
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5]).sample(.1))[0],
(ratio2/p))
# confirm a TF with poles at 0 and p simulates for ratio/p seconds
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5, 0]))[0],
_ideal_tfinal_and_dt(TransferFunction(1, [1, .5, 0]))[0],
(ratio2/p))

# confirm a TF with a natural frequency of wn rad/s gets a
# confirm a TF with a natural frequency of wn rad/s gets a
# dt of 1/(ratio*wn)
wn = 10
ratio_dt = 1/(0.025133 * ratio * wn)
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, 0, wn**2]))[1],
_ideal_tfinal_and_dt(TransferFunction(1, [1, 0, wn**2]))[1],
1/(ratio_dt*ratio*wn))
wn = 100
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, 0, wn**2]))[1],
_ideal_tfinal_and_dt(TransferFunction(1, [1, 0, wn**2]))[1],
1/(ratio_dt*ratio*wn))
zeta = .1
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]))[1],
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]))[1],
1/(ratio_dt*ratio*wn))
# but a smapled one keeps its dt
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]).sample(.1))[1],
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]).sample(.1))[1],
.1)
np.testing.assert_array_almost_equal(
np.diff(initial_response(TransferFunction(1, [1, 2*zeta*wn, wn**2]).sample(.1))[0][0:2]),
np.diff(initial_response(TransferFunction(1, [1, 2*zeta*wn, wn**2]).sample(.1))[0][0:2]),
.1)
np.testing.assert_array_almost_equal(
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]))[1],
_ideal_tfinal_and_dt(TransferFunction(1, [1, 2*zeta*wn, wn**2]))[1],
1/(ratio_dt*ratio*wn))


# TF with fast oscillations simulates only 5000 time steps even with long tfinal
self.assertEqual(5000,
self.assertEqual(5000,
len(_default_time_vector(TransferFunction(1, [1, 0, wn**2]),tfinal=100)))

sys = TransferFunction(1, [1, .5, 0])
sysdt = TransferFunction(1, [1, .5, 0], .1)
# test impose number of time steps
Expand All @@ -430,16 +437,16 @@ def test_auto_generated_time_vector(self):
self.assertNotEqual(15, len(step_response(sysdt, T_num=15)[0]))
# test impose final time
np.testing.assert_array_almost_equal(
100,
100,
np.ceil(step_response(sys, 100)[0][-1]))
np.testing.assert_array_almost_equal(
100,
100,
np.ceil(step_response(sysdt, 100)[0][-1]))
np.testing.assert_array_almost_equal(
100,
100,
np.ceil(impulse_response(sys, 100)[0][-1]))
np.testing.assert_array_almost_equal(
100,
100,
np.ceil(initial_response(sys, 100)[0][-1]))


Expand Down Expand Up @@ -490,7 +497,7 @@ def test_time_vector(self):
np.testing.assert_array_equal(tout, Tin1)

# MIMO forced response
tout, yout, xout = forced_response(self.mimo_dss1, Tin1,
tout, yout, xout = forced_response(self.mimo_dss1, Tin1,
(np.sin(Tin1), np.cos(Tin1)),
mimo_x0)
self.assertEqual(np.shape(tout), np.shape(yout[0,:]))
Expand Down