Fixed bug in mpfr_div_ui for x=0 and u<>0 (sign of result was not set).

Added testcase.
[merged changeset: 4950]


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/2.3@4972 280ebfd0-de03-0410-8827-d642c229c3f4

2 files changed, 8 insertions, 2 deletions

diff --git a/div_ui.c b/div_ui.c
index 6bd632a9a..e17d698fe 100644
--- a/div_ui.c
+++ b/div_ui.c
@@ -1,5 +1,4 @@
-/* mpfr_div_ui -- divide a floating-point number by a machine integer
-   mpfr_div_si -- divide a floating-point number by a machine integer
+/* mpfr_div_{ui,si} -- divide a floating-point number by a machine integer
 
 Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
 Contributed by the Arenaire and Cacao projects, INRIA.
@@ -60,6 +59,7 @@ mpfr_div_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
           else
             {
               MPFR_SET_ZERO(y);
+              MPFR_SET_SAME_SIGN (y, x);
               MPFR_RET(0);
             }
         }
diff --git a/tests/tdiv_ui.c b/tests/tdiv_ui.c
index ba00ed276..492edc1b3 100644
--- a/tests/tdiv_ui.c
+++ b/tests/tdiv_ui.c
@@ -130,6 +130,12 @@ special (void)
         }
     }
 
+  /* Bug reported by Mark Dickinson, 6 Nov 2007 */
+  mpfr_set_si (x, 0, GMP_RNDN);
+  mpfr_set_si (y, -1, GMP_RNDN);
+  mpfr_div_ui (y, x, 4, GMP_RNDN);
+  MPFR_ASSERTN(MPFR_IS_ZERO(y) && MPFR_IS_POS(y));
+
   mpfr_clear (x);
   mpfr_clear (y);
 }