Fixed #1095: make polyint work well with object arrays

2 files changed, 26 insertions, 4 deletions

diff --git a/numpy/lib/polynomial.py b/numpy/lib/polynomial.py
index 5c3d146f8..fee498757 100644
--- a/numpy/lib/polynomial.py
+++ b/numpy/lib/polynomial.py
@@ -241,15 +241,14 @@ def polyint(p, m=1, k=None):
               "k must be a scalar or a rank-1 array of length 1 or >m."
 
     truepoly = isinstance(p, poly1d)
-    p = NX.asarray(p) + 0.0
+    p = NX.asarray(p)
     if m == 0:
         if truepoly:
             return poly1d(p)
         return p
     else:
-        y = NX.zeros(len(p) + 1, p.dtype)
-        y[:-1] = p*1.0/NX.arange(len(p), 0, -1)
-        y[-1] = k[0]
+        # Note: this must work also with object and integer arrays
+        y = NX.concatenate((p.__truediv__(NX.arange(len(p), 0, -1)), [k[0]]))
         val = polyint(y, m - 1, k=k[1:])
         if truepoly:
             return poly1d(val)
diff --git a/numpy/lib/tests/test_polynomial.py b/numpy/lib/tests/test_polynomial.py
index 96dd084b2..45e68d248 100644
--- a/numpy/lib/tests/test_polynomial.py
+++ b/numpy/lib/tests/test_polynomial.py
@@ -110,6 +110,29 @@ class TestDocs(TestCase):
         cc = np.concatenate((c,c), axis=1)
         assert_almost_equal(cc, np.polyfit(x,yy,2))
 
+    def test_objects(self):
+        from decimal import Decimal
+        p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
+        p2 = p * Decimal('1.333333333333333')
+        assert p2[1] == Decimal("3.9999999999999990")
+        p2 = p.deriv()
+        assert p2[1] == Decimal('8.0')
+        p2 = p.integ()
+        assert p2[3] == Decimal("1.333333333333333333333333333")
+        assert p2[2] == Decimal('1.5')
+        assert np.issubdtype(p2.coeffs.dtype, np.object_)
+
+    def test_complex(self):
+        p = np.poly1d([3j, 2j, 1j])
+        p2 = p.integ()
+        assert (p2.coeffs == [1j,1j,1j,0]).all()
+        p2 = p.deriv()
+        assert (p2.coeffs == [6j,2j]).all()
+
+    def test_integ_coeffs(self):
+        p = np.poly1d([3,2,1])
+        p2 = p.integ(3, k=[9,7,6])
+        assert (p2.coeffs == [1/4./5.,1/3./4.,1/2./3.,9/1./2.,7,6]).all()
 
 if __name__ == "__main__":
     run_module_suite()