ENH: Add reduce method to polynomial.Chebyshev and

polynomial.Polynomial. This method behaves like truncate except
it takes the degree of the result instead of the number of
coefficients.

2 files changed, 16 insertions, 0 deletions

diff --git a/numpy/polynomial/tests/test_chebyshev.py b/numpy/polynomial/tests/test_chebyshev.py
index d61e8b07c..5662d0362 100644
--- a/numpy/polynomial/tests/test_chebyshev.py
+++ b/numpy/polynomial/tests/test_chebyshev.py
@@ -402,6 +402,14 @@ class TestChebyshevClass(TestCase) :
     def test_degree(self) :
         assert_equal(self.p1.degree(), 2)
 
+    def test_reduce(self) :
+        assert_raises(ValueError, self.p1.reduce, .5)
+        assert_raises(ValueError, self.p1.reduce, -1)
+        assert_equal(len(self.p1.reduce(3)), 3)
+        assert_equal(len(self.p1.reduce(2)), 3)
+        assert_equal(len(self.p1.reduce(1)), 2)
+        assert_equal(len(self.p1.reduce(0)), 1)
+
     def test_convert(self) :
         x = np.linspace(-1,1)
         p = self.p1.convert(domain=[0,1])
diff --git a/numpy/polynomial/tests/test_polynomial.py b/numpy/polynomial/tests/test_polynomial.py
index 530e5d949..15525fcd8 100644
--- a/numpy/polynomial/tests/test_polynomial.py
+++ b/numpy/polynomial/tests/test_polynomial.py
@@ -373,6 +373,14 @@ class TestPolynomialClass(TestCase) :
     def test_degree(self) :
         assert_equal(self.p1.degree(), 2)
 
+    def test_reduce(self) :
+        assert_raises(ValueError, self.p1.reduce, .5)
+        assert_raises(ValueError, self.p1.reduce, -1)
+        assert_equal(len(self.p1.reduce(3)), 3)
+        assert_equal(len(self.p1.reduce(2)), 3)
+        assert_equal(len(self.p1.reduce(1)), 2)
+        assert_equal(len(self.p1.reduce(0)), 1)
+
     def test_convert(self) :
         x = np.linspace(-1,1)
         p = self.p1.convert(domain=[0,1])