BUG: Campanion Matrix was scalar, not matrix for degree 1.

The companion matrices returned by the various polynomial types was
a scalar in the degree one case instead of a 2-D array. Fix that and
add a test to check for that result.

Closes #3459.

1 files changed, 16 insertions, 0 deletions

diff --git a/numpy/polynomial/tests/test_chebyshev.py b/numpy/polynomial/tests/test_chebyshev.py
index 23a17b464..367d81f58 100644
--- a/numpy/polynomial/tests/test_chebyshev.py
+++ b/numpy/polynomial/tests/test_chebyshev.py
@@ -440,6 +440,22 @@ class TestFitting(TestCase):
         x = [1, 1j, -1, -1j]
         assert_almost_equal(cheb.chebfit(x, x, 1), [0, 1])
 
+
+class TestCompanion(TestCase):
+
+    def test_raises(self):
+        assert_raises(ValueError, cheb.chebcompanion, [])
+        assert_raises(ValueError, cheb.chebcompanion, [1])
+
+    def test_dimensions(self):
+        for i in range(1, 5):
+            coef = [0]*i + [1]
+            assert_(cheb.chebcompanion(coef).shape == (i, i))
+
+    def test_linear_root(self):
+        assert_(cheb.chebcompanion([1, 2])[0, 0] == -.5)
+
+
 class TestGauss(TestCase):
 
     def test_100(self):