Add doc-strings to some cl float parameters.

* lisp/emacs-lisp/cl-extra.el (cl-float-limits): Add doc string.
* lisp/emacs-lisp/cl.el (most-positive-float, most-negative-float)
(least-positive-float, least-negative-float)
(least-positive-normalized-float, least-negative-normalized-float)
(float-epsilon, float-negative-epsilon): Add doc-strings,
based on those in cl.texi.

* lisp/emacs-lisp/cl-extra.el (most-positive-float, most-negative-float)
(least-positive-float, least-negative-float)
(least-positive-normalized-float, least-negative-normalized-float)
(float-epsilon, float-negative-epsilon):
Remove unnecessary declarations.

3 files changed, 63 insertions, 18 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index cbfc662da5..6aa1bddb9f 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,18 @@
 2011-10-27  Glenn Morris  <[email protected]>
 
+	* emacs-lisp/cl-extra.el (most-positive-float, most-negative-float)
+	(least-positive-float, least-negative-float)
+	(least-positive-normalized-float, least-negative-normalized-float)
+	(float-epsilon, float-negative-epsilon):
+	Remove unnecessary declarations.
+
+	* emacs-lisp/cl-extra.el (cl-float-limits): Add doc string.
+	* emacs-lisp/cl.el (most-positive-float, most-negative-float)
+	(least-positive-float, least-negative-float)
+	(least-positive-normalized-float, least-negative-normalized-float)
+	(float-epsilon, float-negative-epsilon): Add doc-strings,
+	based on those in cl.texi.
+
 	* files.el (set-visited-file-name): If the major-mode changed,
 	reload the local variables.  (Bug#9796)
 
diff --git a/lisp/emacs-lisp/cl-extra.el b/lisp/emacs-lisp/cl-extra.el
index 7468a0237c..8ea58b2e07 100644
--- a/lisp/emacs-lisp/cl-extra.el
+++ b/lisp/emacs-lisp/cl-extra.el
@@ -480,17 +480,13 @@ If STATE is t, return a new state object seeded from the time of day."
 	(and (numberp res) (/= res (/ res 2)) res))
     (arith-error nil)))
 
-(defvar most-positive-float)
-(defvar most-negative-float)
-(defvar least-positive-float)
-(defvar least-negative-float)
-(defvar least-positive-normalized-float)
-(defvar least-negative-normalized-float)
-(defvar float-epsilon)
-(defvar float-negative-epsilon)
-
 ;;;###autoload
 (defun cl-float-limits ()
+  "Initialize the Common Lisp floating-point parameters.
+This sets the values of: `most-positive-float', `most-negative-float',
+`least-positive-float', `least-negative-float', `float-epsilon',
+`float-negative-epsilon', `least-positive-normalized-float', and
+`least-negative-normalized-float'."
   (or most-positive-float (not (numberp '2e1))
       (let ((x '2e0) y z)
 	;; Find maximum exponent (first two loops are optimizations)
diff --git a/lisp/emacs-lisp/cl.el b/lisp/emacs-lisp/cl.el
index 526475eb1b..0b34e9f27f 100644
--- a/lisp/emacs-lisp/cl.el
+++ b/lisp/emacs-lisp/cl.el
@@ -333,15 +333,51 @@ always returns nil."
 
 (defvar *random-state* (vector 'cl-random-state-tag -1 30 (cl-random-time)))
 
-;; The following are actually set by cl-float-limits.
-(defconst most-positive-float nil)
-(defconst most-negative-float nil)
-(defconst least-positive-float nil)
-(defconst least-negative-float nil)
-(defconst least-positive-normalized-float nil)
-(defconst least-negative-normalized-float nil)
-(defconst float-epsilon nil)
-(defconst float-negative-epsilon nil)
+(defconst most-positive-float nil
+  "The largest value that a Lisp float can hold.
+If your system supports infinities, this is the largest finite value.
+For IEEE machines, this is approximately 1.79e+308.
+Call `cl-float-limits' to set this.")
+
+(defconst most-negative-float nil
+  "The largest negative value that a Lisp float can hold.
+This is simply -`most-negative-float'.
+Call `cl-float-limits' to set this.")
+
+(defconst least-positive-float nil
+  "The smallest value greater than zero that a Lisp float can hold.
+For IEEE machines, it is about 4.94e-324 if denormals are supported,
+or 2.22e-308 if they are not.
+Call `cl-float-limits' to set this.")
+
+(defconst least-negative-float nil
+  "The smallest value less than zero that a Lisp float can hold.
+This is simply -`least-positive-float'.
+Call `cl-float-limits' to set this.")
+
+(defconst least-positive-normalized-float nil
+  "The smallest normalized Lisp float greater than zero.
+This is the smallest value for which IEEE denormalization does not lose
+precision.  For IEEE machines, this value is about 2.22e-308.
+For machines that do not support the concept of denormalization
+and gradual underflow, this constant equals `least-positive-float'.
+Call `cl-float-limits' to set this.")
+
+(defconst least-negative-normalized-float nil
+  "The smallest normalized Lisp float less than zero.
+This is simply -`least-positive-normalized-float'.
+Call `cl-float-limits' to set this.")
+
+(defconst float-epsilon nil
+  "The smallest positive float that adds to 1.0 to give a distinct value.
+Adding a number less than this to 1.0 returns 1.0 due to roundoff.
+For IEEE machines, epsilon is about 2.22e-16.
+Call `cl-float-limits' to set this.")
+
+(defconst float-negative-epsilon nil
+  "The smallest positive float that subtracts from 1.0 to give a distinct value.
+For IEEE machines, it is about 1.11e-16.
+Call `cl-float-limits' to set this.")
 
 
 ;;; Sequence functions.