BUG: Return the coefficients array directly

Turns out that this was relied upon downstream

We also add a setter for coeffs, so that augmented assignment does not both
change state and raise an exception suggesting state could not be changed.

1 files changed, 8 insertions, 2 deletions

diff --git a/numpy/lib/polynomial.py b/numpy/lib/polynomial.py
index f49b7e295..1b13b38a0 100644
--- a/numpy/lib/polynomial.py
+++ b/numpy/lib/polynomial.py
@@ -1040,8 +1040,14 @@ class poly1d(object):
 
     @property
     def coeffs(self):
-        """ A copy of the polynomial coefficients """
-        return self._coeffs.copy()
+        """ The polynomial coefficients """
+        return self._coeffs
+
+    @coeffs.setter
+    def coeffs(self, value):
+        # allowing this makes p.coeffs *= 2 legal
+        if value is not self._coeffs:
+            raise AttributeError("Cannot set attribute")
 
     @property
     def variable(self):