BUG: avoid X += X.T (refs #4401)

perimosocordiae · perimosocordiae · commit 28b10283e5f1 · 2015-01-14T14:05:57.000-05:00
diff --git a/scipy/sparse/linalg/dsolve/tests/test_linsolve.py b/scipy/sparse/linalg/dsolve/tests/test_linsolve.py
@@ -346,7 +346,8 @@ def test_splu_perm(self):
 
         # Now make a symmetric, and test that the two permutation vectors are
         # the same
-        a += a.T
+        # Note: a += a.T relies on undefined behavior.
+        a = a + a.T
         a_ = csc_matrix(a)
         lu = splu(a_)
         assert_array_equal(lu.perm_r, lu.perm_c)
