Add tests showing problems with ctrlutil.unwrap

cwrowley · cwrowley · commit 51536bfdd41c · 2015-04-08T21:34:16.000-04:00
The routine ctrlutil.unwrap fails if there are large jumps in phase.
diff --git a/control/tests/ctrlutil_test.py b/control/tests/ctrlutil_test.py
@@ -0,0 +1,43 @@
+import unittest
+import numpy as np
+from control.ctrlutil import *
+
+class TestUtils(unittest.TestCase):
+    def setUp(self):
+        self.mag = np.array([1, 10, 100, 2, 0.1, 0.01])
+        self.db = np.array([0, 20, 40, 6.0206, -20, -40])
+
+    def check_unwrap_array(self, angle, period=None):
+        if period is None:
+            angle_mod = angle % (2 * np.pi)
+            angle_unwrap = unwrap(angle_mod)
+        else:
+            angle_mod = angle % period
+            angle_unwrap = unwrap(angle_mod, period)
+        np.testing.assert_array_almost_equal(angle_unwrap, angle)
+
+    def test_unwrap_increasing(self):
+        angle = np.linspace(0, 20, 50)
+        self.check_unwrap_array(angle)
+
+    def test_unwrap_decreasing(self):
+        angle = np.linspace(0, -20, 50)
+        self.check_unwrap_array(angle)
+
+    def test_unwrap_inc_degrees(self):
+        angle = np.linspace(0, 720, 50)
+        self.check_unwrap_array(angle, 360)
+
+    def test_unwrap_dec_degrees(self):
+        angle = np.linspace(0, -720, 50)
+        self.check_unwrap_array(angle, 360)
+
+    def test_unwrap_large_skips(self):
+        angle = np.array([0., 4 * np.pi, -2 * np.pi])
+        np.testing.assert_array_almost_equal(unwrap(angle), [0., 0., 0.])
+
+def test_suite():
+    return unittest.TestLoader().loadTestsFromTestCase(TestUtils)
+
+if __name__ == "__main__":
+    unittest.main()
