[cos.c] fixed case where reduced argument is zero

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@6535 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 2 insertions, 0 deletions

diff --git a/cos.c b/cos.c
index b0aeaa939..1057baf06 100644
--- a/cos.c
+++ b/cos.c
@@ -203,6 +203,8 @@ mpfr_cos (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
           mpfr_const_pi (c, MPFR_RNDN);
           mpfr_mul_2ui (c, c, 1, MPFR_RNDN); /* 2Pi */
           mpfr_remainder (xr, x, c, MPFR_RNDN);
+          if (MPFR_IS_ZERO(xr))
+            goto ziv_next;
           /* now |xr| <= 4, thus r <= 16 below */
           mpfr_mul (r, xr, xr, MPFR_RNDU); /* err <= 1 ulp */
         }