lisp/emacs-lisp/float-sup.el

   1 ;;; float-sup.el --- define some constants useful for floating point numbers.
   2
   3 ;; Copyright (C) 1985, 1986, 1987, 2001, 2002, 2003, 2004, 2005, 2006,
   4 ;;   2007, 2008, 2009, 2010  Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7 ;; Keywords: internal
   8 ;; Package: emacs
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 ;; Provide an easy hook to tell if we are running with floats or not.
  30 ;; Define pi and e via math-lib calls (much less prone to killer typos).
  31 (defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")
  32 (defconst pi float-pi "Obsolete since Emacs-23.3.  Use `float-pi' instead.")
  33
  34 (defconst float-e (exp 1) "The value of e (2.7182818...).")
  35
  36 (defconst degrees-to-radians (/ float-pi 180.0)
  37   "Degrees to radian conversion constant.")
  38 (defconst radians-to-degrees (/ 180.0 float-pi)
  39   "Radian to degree conversion constant.")
  40
  41 ;; These expand to a single multiply by a float when byte compiled.
  42
  43 (defmacro degrees-to-radians (x)
  44   "Convert X from degrees to radians."
  45   (list '* degrees-to-radians x))
  46 (defmacro radians-to-degrees (x)
  47   "Convert X from radians to degrees."
  48   (list '* radians-to-degrees x))
  49
  50 (provide 'lisp-float-type)
  51
  52 ;;; float-sup.el ends here