[Emacs-diffs] trunk r116804: Fix porting inconsistency about rounding to even.

[Paul Eggert]

------------------------------------------------------------
revno: 116804
revision-id: address@hidden
parent: address@hidden
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Wed 2014-03-19 14:09:08 -0700
message:
  Fix porting inconsistency about rounding to even.
  
  * doc/lispref/numbers.texi (Numeric Conversions, Rounding Operations):
  Document that 'round' and 'fround' round to even.
  * src/floatfns.c (emacs_rint) [!HAVE_RINT]: Round to even.
  This way, the unusual !HAVE_RINT case acts like the usual
  HAVE_RINT case, and we can fix the documentation accordingly.
modified:
  doc/lispref/ChangeLog          changelog-20091113204419-o5vbwnq5f7feedwu-6155
  doc/lispref/numbers.texi       
numbers.texi-20091113204419-o5vbwnq5f7feedwu-6203
  src/ChangeLog                  changelog-20091113204419-o5vbwnq5f7feedwu-1438
  src/floatfns.c                 floatfns.c-20091113204419-o5vbwnq5f7feedwu-141

=== modified file 'doc/lispref/ChangeLog'
--- a/doc/lispref/ChangeLog     2014-03-18 23:31:17 +0000
+++ b/doc/lispref/ChangeLog     2014-03-19 21:09:08 +0000
@@ -1,3 +1,9 @@
+2014-03-19  Paul Eggert  <address@hidden>
+
+       Fix porting inconsistency about rounding to even.
+       * numbers.texi (Numeric Conversions, Rounding Operations):
+       Document that 'round' and 'fround' round to even.
+
 2014-03-18  Juanma Barranquero  <address@hidden>
 
        * customize.texi (Variable Definitions): Recommend avoiding

=== modified file 'doc/lispref/numbers.texi'
--- a/doc/lispref/numbers.texi  2014-03-18 04:03:59 +0000
+++ b/doc/lispref/numbers.texi  2014-03-19 21:09:08 +0000
@@ -534,8 +534,7 @@
 @defun round number &optional divisor
 This returns @var{number}, converted to an integer by rounding towards the
 nearest integer.  Rounding a value equidistant between two integers
-may choose the integer closer to zero, or it may prefer an even integer,
-depending on your machine.
+returns the even integer.
 
 @example
 (round 1.2)
@@ -803,6 +802,7 @@
 @defun fround float
 This function rounds @var{float} to the nearest integral value,
 and returns that value as a floating-point number.
+Rounding a value equidistant between two integers returns the even integer.
 @end defun
 
 @node Bitwise Operations

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2014-03-19 17:43:18 +0000
+++ b/src/ChangeLog     2014-03-19 21:09:08 +0000
@@ -1,3 +1,10 @@
+2014-03-19  Paul Eggert  <address@hidden>
+
+       Fix porting inconsistency about rounding to even.
+       * floatfns.c (emacs_rint) [!HAVE_RINT]: Round to even.
+       This way, the unusual !HAVE_RINT case acts like the usual
+       HAVE_RINT case, and we can fix the documentation accordingly.
+
 2014-03-19  Eli Zaretskii  <address@hidden>
 
        * w32fns.c (reset_modifiers): Zero out keystate[] before using it.

=== modified file 'src/floatfns.c'
--- a/src/floatfns.c    2014-01-01 07:43:34 +0000
+++ b/src/floatfns.c    2014-03-19 21:09:08 +0000
@@ -428,7 +428,9 @@
 static double
 emacs_rint (double d)
 {
-  return floor (d + 0.5);
+  double d1 = d + 0.5;
+  double r = floor (d1);
+  return r - (r == d1 && fmod (r, 2) != 0);
 }
 #endif