allow bigger relative tolerance for discrete margin test

bnavigator · bnavigator · commit d96bc7095564 · 2020-11-17T12:46:52.000+01:00
diff --git a/control/tests/margin_test.py b/control/tests/margin_test.py
@@ -337,4 +337,5 @@ def test_stability_margins_discrete(cnum, cden, dt, ref):
     """Test stability_margins with discrete TF input"""
     tf = TransferFunction(cnum, cden).sample(dt)
     out = stability_margins(tf)
-    assert_allclose(out, ref, atol=1.5e-2)
+    # the numeric precision is really not that great
+    assert_allclose(out, ref, rtol=2e-2)
