misc bugfixes: fixed prewarp not working in c2d and sample_system, incorrect order of return arguments in margin, typos and changed to ControlMIMONotImplemented error where needed.

sawyerbfuller · sawyerbfuller · commit ca8e67025c1b · 2021-11-05T13:00:54.000-07:00
diff --git a/control/dtime.py b/control/dtime.py
@@ -89,7 +89,8 @@ def sample_system(sysc, Ts, method='zoh', alpha=None, prewarp_frequency=None):
     if not isctime(sysc):
         raise ValueError("First argument must be continuous time system")
 
-    return sysc.sample(Ts, method, alpha, prewarp_frequency)
+    return sysc.sample(Ts,
+        method=method, alpha=alpha, prewarp_frequency=prewarp_frequency)
 
 
 def c2d(sysc, Ts, method='zoh', prewarp_frequency=None):
@@ -126,6 +127,7 @@ def c2d(sysc, Ts, method='zoh', prewarp_frequency=None):
     """
 
     #  Call the sample_system() function to do the work
-    sysd = sample_system(sysc, Ts, method, prewarp_frequency)
+    sysd = sample_system(sysc, Ts,
+        method=method, prewarp_frequency=prewarp_frequency)
 
     return sysd
diff --git a/control/margins.py b/control/margins.py
@@ -283,7 +283,7 @@ def stability_margins(sysdata, returnall=False, epsw=0.0, method='best'):
     -------
     gm : float or array_like
         Gain margin
-    pm : float or array_loke
+    pm : float or array_like
         Phase margin
     sm : float or array_like
         Stability margin, the minimum distance from the Nyquist plot to -1
@@ -522,10 +522,10 @@ def margin(*args):
         Gain margin
     pm : float
         Phase margin (in degrees)
-    wpc : float or array_like
-        Phase crossover frequency (where phase crosses -180 degrees)
     wgc : float or array_like
         Gain crossover frequency (where gain crosses 1)
+    wpc : float or array_like
+        Phase crossover frequency (where phase crosses -180 degrees)
 
     Margins are calculated for a SISO open-loop system.
 
@@ -548,4 +548,4 @@ def margin(*args):
         raise ValueError("Margin needs 1 or 3 arguments; received %i."
                          % len(args))
 
-    return margin[0], margin[1], margin[3], margin[4]
+    return margin[0], margin[1], margin[4], margin[3]
diff --git a/control/tests/margin_test.py b/control/tests/margin_test.py
@@ -102,15 +102,15 @@ def test_margin_sys(tsys):
     sys, refout, refoutall = tsys
     """Test margin() function with system input"""
     out = margin(sys)
-    assert_allclose(out, np.array(refout)[[0, 1, 3, 4]], atol=1.5e-3)
+    assert_allclose(out, np.array(refout)[[0, 1, 4, 3]], atol=1.5e-3)
 
 def test_margin_3input(tsys):
     sys, refout, refoutall = tsys
     """Test margin() function with mag, phase, omega input"""
     omega = np.logspace(-2, 2, 2000)
     mag, phase, omega_ = sys.frequency_response(omega)
     out = margin((mag, phase*180/np.pi, omega_))
-    assert_allclose(out, np.array(refout)[[0, 1, 3, 4]], atol=1.5e-3)
+    assert_allclose(out, np.array(refout)[[0, 1, 4, 3]], atol=1.5e-3)
 
 
 @pytest.mark.parametrize(
@@ -276,23 +276,23 @@ def tsys_zmore(request, tsys_zmoresystems):
 @pytest.mark.parametrize(
     'tsys_zmore',
     [dict(sysname='typem1', K=2.0, atol=1.5e-3,
-          result=(float('Inf'), -120.0007, float('NaN'), 0.5774)),
+          result=(float('Inf'), -120.0007,  0.5774, float('NaN'))),
      dict(sysname='type0', K=0.8, atol=1.5e-3,
-          result=(10.0014, float('inf'), 1.7322, float('nan'))),
+          result=(10.0014, float('inf'), float('nan'), 1.7322)),
      dict(sysname='type0', K=2.0, atol=1e-2,
-          result=(4.000, 67.6058, 1.7322, 0.7663)),
+          result=(4.000, 67.6058, 0.7663, 1.7322)),
      dict(sysname='type1', K=1.0, atol=1e-4,
-          result=(float('Inf'), 144.9032, float('NaN'), 0.3162)),
+          result=(float('Inf'), 144.9032, 0.3162, float('NaN'))),
      dict(sysname='type2', K=1.0, atol=1e-4,
-          result=(float('Inf'), 44.4594, float('NaN'), 0.7907)),
+          result=(float('Inf'), 44.4594, 0.7907, float('NaN'))),
      dict(sysname='type3', K=1.0, atol=1.5e-3,
-          result=(0.0626, 37.1748, 0.1119, 0.7951)),
+          result=(0.0626, 37.1748, 0.7951, 0.1119)),
      dict(sysname='example21', K=1.0, atol=1e-2,
           result=(0.0100, -14.5640, 0, 0.0022)),
      dict(sysname='example21', K=1000.0, atol=1e-2,
-          result=(0.1793, 22.5215, 0.0243, 0.0630)),
+          result=(0.1793, 22.5215, 0.0630, 0.0243)),
      dict(sysname='example21', K=5000.0, atol=1.5e-3,
-          result=(4.5596, 21.2101, 0.4385, 0.1868)),
+          result=(4.5596, 21.2101, 0.1868, 0.4385)),
      ],
     indirect=True)
 def test_zmore_margin(tsys_zmore):
diff --git a/control/tests/matlab_test.py b/control/tests/matlab_test.py
@@ -361,7 +361,7 @@ def testMargin(self, siso):
         gm, pm, wg, wp = margin(siso.ss2)
         gm, pm, wg, wp = margin(siso.ss2 * siso.ss2 * 2)
         np.testing.assert_array_almost_equal(
-            [gm, pm, wg, wp], [1.5451, 75.9933, 1.2720, 0.6559], decimal=3)
+            [gm, pm, wg, wp], [1.5451, 75.9933, 0.6559, 1.2720], decimal=3)
 
     def testDcgain(self, siso):
         """Test dcgain() for SISO system"""
@@ -785,8 +785,8 @@ def testCombi01(self):
         # print("%f %f %f %f" % (gm, pm, wg, wp))
         np.testing.assert_allclose(gm, 3.32065569155)
         np.testing.assert_allclose(pm, 46.9740430224)
-        np.testing.assert_allclose(wg, 0.176469728448)
-        np.testing.assert_allclose(wp, 0.0616288455466)
+        np.testing.assert_allclose(wg, 0.0616288455466)
+        np.testing.assert_allclose(wp, 0.176469728448)
 
     def test_tf_string_args(self):
         """Make sure s and z are defined properly"""
diff --git a/control/xferfcn.py b/control/xferfcn.py
@@ -64,6 +64,7 @@
 from itertools import chain
 from re import sub
 from .lti import LTI, common_timebase, isdtime, _process_frequency_response
+from .exception import ControlMIMONotImplemented
 from . import config
 
 __all__ = ['TransferFunction', 'tf', 'ss2tf', 'tfdata']
@@ -793,9 +794,9 @@ def feedback(self, other=1, sign=-1):
         if (self.ninputs > 1 or self.noutputs > 1 or
                 other.ninputs > 1 or other.noutputs > 1):
             # TODO: MIMO feedback
-            raise NotImplementedError(
-                "TransferFunction.feedback is currently only implemented "
-                "for SISO functions.")
+            raise ControlMIMONotImplemented(
+                "TransferFunction.feedback is currently not implemented for "
+                "MIMO systems.")
         dt = common_timebase(self.dt, other.dt)
 
         num1 = self.num[0][0]
@@ -1117,7 +1118,7 @@ def sample(self, Ts, method='zoh', alpha=None, prewarp_frequency=None):
         if not self.isctime():
             raise ValueError("System must be continuous time system")
         if not self.issiso():
-            raise NotImplementedError("MIMO implementation not available")
+            raise ControlMIMONotImplemented("Not implemented for MIMO systems")
         if method == "matched":
             return _c2d_matched(self, Ts)
         sys = (self.num[0][0], self.den[0][0])
@@ -1373,7 +1374,8 @@ def _convert_to_transfer_function(sys, **kw):
             except ImportError:
                 # If slycot is not available, use signal.lti (SISO only)
                 if sys.ninputs != 1 or sys.noutputs != 1:
-                    raise TypeError("No support for MIMO without slycot.")
+                    raise ControlMIMONotImplemented("Not implemented for " +
+                        "MIMO systems without slycot.")
 
                 # Do the conversion using sp.signal.ss2tf
                 # Note that this returns a 2D array for the numerator
