From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 8 Sep 2012 19:57:32 +0000 (-0700)
Subject: * floatfns.c (Ftan): Use tan (x), not (sin (x) / cos (x)).
X-Git-Tag: emacs-24.2.90~358
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=eabf0404414f2828c08d1d5d8fab4740670e7541;p=emacs.git

* floatfns.c (Ftan): Use tan (x), not (sin (x) / cos (x)).

This produces more-accurate results.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index dd4719e25c6..0316e7708af 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2012-09-08  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* floatfns.c (Ftan): Use tan (x), not (sin (x) / cos (x)).
+	This produces more-accurate results.
+
 2012-09-08  Jan Djärv  <jan.h.d@swipnet.se>
 
 	* nsterm.m (updateFrameSize): Call setFrame: on the view when size
diff --git a/src/floatfns.c b/src/floatfns.c
index 3a95d828c0c..dfe063b152f 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -265,12 +265,12 @@ DEFUN ("tan", Ftan, Stan, 1, 1, 0,
   (register Lisp_Object arg)
 {
   double d = extract_float (arg);
-  double c = cos (d);
 #ifdef FLOAT_CHECK_DOMAIN
+  double c = cos (d);
   if (c == 0.0)
     domain_error ("tan", arg);
 #endif
-  IN_FLOAT (d = sin (d) / c, "tan", arg);
+  IN_FLOAT (d = tan (d), "tan", arg);
   return make_float (d);
 }