lisp/emacs-lisp/float-sup.el

   1 ;;; float-sup.el --- define some constants useful for floating point numbers.
   2
   3 ;; Copyright (C) 1985-1987, 2001-2014 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: internal
   7 ;; Package: emacs
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 ;; Provide an easy hook to tell if we are running with floats or not.
  29 ;; Define pi and e via math-lib calls (much less prone to killer typos).
  30 (defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")
  31 (defconst pi float-pi
  32   "Obsolete since Emacs-23.3.  Use `float-pi' instead.")
  33 (internal-make-var-non-special 'pi)
  34
  35 (defconst float-e (exp 1) "The value of e (2.7182818...).")
  36
  37 (defconst degrees-to-radians (/ float-pi 180.0)
  38   "Degrees to radian conversion constant.")
  39 (defconst radians-to-degrees (/ 180.0 float-pi)
  40   "Radian to degree conversion constant.")
  41
  42 ;; These expand to a single multiply by a float when byte compiled.
  43
  44 (defmacro degrees-to-radians (x)
  45   "Convert X from degrees to radians."
  46   (list '* degrees-to-radians x))
  47 (defmacro radians-to-degrees (x)
  48   "Convert X from radians to degrees."
  49   (list '* radians-to-degrees x))
  50
  51 (provide 'lisp-float-type)
  52
  53 ;;; float-sup.el ends here