(/ N) now returns the reciprocal of N

This is more compatible with Common Lisp and XEmacs (Bug#21690).  See:
http://lists.gnu.org/archive/html/emacs-devel/2015-10/msg01053.html
* lisp/color.el (color-hue-to-rgb, color-hsl-to-rgb)
(color-xyz-to-srgb, color-xyz-to-lab):
* lisp/emacs-lisp/cl-extra.el (cl-float-limits):
* lisp/net/shr-color.el (shr-color-hue-to-rgb)
(shr-color-hsl-to-rgb-fractions):
Exploit the change to simplify the code a bit.
* lisp/emacs-lisp/bytecomp.el (byte-compile-quo):
Don’t complain about single-argument calls to ‘/’.
* src/data.c (arith_driver, float_arith_driver):
Implement the change.

1 files changed, 13 insertions, 4 deletions

diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi
index 3c70d2f0a06..54c8d3e5988 100644
--- a/doc/lispref/numbers.texi
+++ b/doc/lispref/numbers.texi
@@ -642,10 +642,11 @@ product.  When given no arguments, @code{*} returns 1.
 @end example
 @end defun
 
-@defun / dividend divisor &rest divisors
-This function divides @var{dividend} by @var{divisor} and returns the
-quotient.  If there are additional arguments @var{divisors}, then it
-divides @var{dividend} by each divisor in turn.  Each argument may be a
+@defun / number &rest divisors
+With one or more @var{divisors}, this function divides @var{number}
+by each divisor in @var{divisors} in turn, and returns the quotient.
+With no @var{divisors}, this function returns 1/@var{number}, i.e.,
+the multiplicative inverse of @var{number}.  Each argument may be a
 number or a marker.
 
 If all the arguments are integers, the result is an integer, obtained
@@ -673,6 +674,14 @@ by rounding the quotient towards zero after each division.
      @result{} 2.5
 @end group
 @group
+(/ 4.0)
+     @result{} 0.25
+@end group
+@group
+(/ 4)
+     @result{} 0
+@end group
+@group
 (/ 25 3 2)
      @result{} 4
 @end group