Fix bug with x<0 and k even

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@3647 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 7 insertions, 0 deletions

diff --git a/root.c b/root.c
index 6a591b0ef..2d0506861 100644
--- a/root.c
+++ b/root.c
@@ -107,6 +107,13 @@ mpfr_root (mpfr_ptr y, mpfr_srcptr x, unsigned long k, mp_rnd_t rnd_mode)
 	}
     }
 
+  /* Returns NAN for x < 0 and k even */
+  else if (MPFR_IS_NEG (x) && (k % 2 == 0))
+    {
+      MPFR_SET_NAN (y);
+      MPFR_RET_NAN;
+    }
+
   /* General case */
   MPFR_SAVE_EXPO_MARK (expo);
   mpz_init (m);