Fix arb.neg()

README.md

@@ -167,6 +167,7 @@ Contributors (0.9.0):
 - Rémy Oudompheng (RO)
 - Agriya Khetarpal (AK)
 - Oscar Benjamin (OB)
+- Daniel Simmons-Marengo (DSM)
 
 Changes (0.9.0):
 
@@ -181,6 +182,9 @@ Changes (0.9.0):
 - [gh-312](https://github.com/flintlib/python-flint/pull/312),
   Add `discriminant` method to `fmpz_poly`, `fmpq_poly` and
   `nmod_poly`. (RO)
+- [gh-336](https://github.com/flintlib/python-flint/pull/336),
+  Fixed a bug in `arb.neg()` which caused it to return its input
+  without negating it. (DSM)
 
 0.8.0
 -----

src/flint/test/test_all.py

@@ -1669,6 +1669,8 @@ def test_arb():
     assert arb(3) <= arb("inf")
     assert arb(3) == arb(3)
     assert arb(3) != arb(2)
+    assert -arb(3) == arb(-3)
+    assert arb(3).neg() == arb(-3)
     assert not (arb("1.1") == arb("1.1"))
 
     assert arb(3).repr() == 'arb((0x3, 0x0))'

src/flint/types/arb.pyx

@@ -567,9 +567,9 @@ cdef class arb(flint_scalar):
     def neg(self, bint exact=False):
         res = arb.__new__(arb)
         if exact:
-            arb_set((<arb>res).val, (<arb>self).val)
+            arb_neg((<arb>res).val, (<arb>self).val)
         else:
-            arb_set_round((<arb>res).val, (<arb>self).val, getprec())
+            arb_neg_round((<arb>res).val, (<arb>self).val, getprec())
         return res
 
     def __abs__(self):