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diff --git a/lisp/float-sup.el b/lisp/float-sup.el
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+;; Basic editing commands for Emacs
+;; Copyright (C) 1985, 1986, 1987 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 1, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to
+;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+;; Provide a meaningful error message if we are running on
+;; bare (non-float) emacs.
+;; Can't test for 'floatp since that may be defined by float-imitation
+;; packages like float.el in this very directory.
+
+(if (fboundp 'atan)
+    nil
+  (error "Floating point was disabled at compile time"))
+
+;; provide an easy hook to tell if we are running with floats or not.
+(provide 'lisp-float-type)
+
+;; define pi and e via math-lib calls. (much less prone to killer typos.)
+(defconst pi (* 4 (atan 1)) "The value of Pi (3.1415926...)")
+(defconst e (exp 1) "The value of e (2.7182818...)")
+
+;; Careful when editing this file ... typos here will be hard to spot.
+;; (defconst pi       3.14159265358979323846264338327
+;;  "The value of Pi (3.14159265358979323846264338327...)")
+
+(defconst degrees-to-radians (/ pi 180.0)
+  "Degrees to radian conversion constant")
+(defconst radians-to-degrees (/ 180.0 pi)
+  "Radian to degree conversion constant")
+
+;; these expand to a single multiply by a float
+;; when byte compiled
+
+(defmacro degrees-to-radians (x)
+  "Convert ARG from degrees to radians."
+  (list '* (/ pi 180.0) x))
+(defmacro radians-to-degrees (x)
+  "Convert ARG from radians to degrees."
+  (list '* (/ 180.0 pi) x))