Add support for FAST_COMPUTE_IS_SMALL_INPUT.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@3552 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 6 insertions, 3 deletions

diff --git a/tanh.c b/tanh.c
index b7c59a239..b4c01101d 100644
--- a/tanh.c
+++ b/tanh.c
@@ -38,7 +38,7 @@ mpfr_tanh (mpfr_ptr y, mpfr_srcptr xt , mp_rnd_t rnd_mode)
     {
       if (MPFR_IS_NAN (xt)) 
 	{
-	  MPFR_SET_NAN (y); 
+	  MPFR_SET_NAN (y);
 	  MPFR_RET_NAN;
 	}
       else if (MPFR_IS_INF (xt))
@@ -54,10 +54,13 @@ mpfr_tanh (mpfr_ptr y, mpfr_srcptr xt , mp_rnd_t rnd_mode)
 	  MPFR_RET (0);
 	}
     }
-  
+
+  /* tanh(x) = x - x^3/3 + ... so the error is < 2^(3*EXP(x)-1) */
+  MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, xt, -2*MPFR_GET_EXP(xt)+1,0,rnd_mode, );
+
   MPFR_SAVE_EXPO_MARK (expo);
   MPFR_TMP_INIT_ABS (x, xt);
-  
+
   /* General case */
   {
     /* Declaration of the intermediary variable */