lisp/float-sup.el

   1 ;;; float-sup.el --- detect absence of floating-point support in Emacs runtime
   2
   3 ;; Copyright (C) 1985, 1986, 1987 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 ;; Provide a meaningful error message if we are running on
  29 ;; bare (non-float) emacs.
  30 ;; Can't test for 'floatp since that may be defined by float-imitation
  31 ;; packages like float.el in this very directory.
  32
  33 (if (fboundp 'atan)
  34     nil
  35   (error "Floating point was disabled at compile time"))
  36
  37 ;; provide an easy hook to tell if we are running with floats or not.
  38 ;; define pi and e via math-lib calls. (much less prone to killer typos.)
  39 (defconst pi (* 4 (atan 1)) "The value of Pi (3.1415926...)")
  40 (defconst e (exp 1) "The value of e (2.7182818...)")
  41
  42 ;; Careful when editing this file ... typos here will be hard to spot.
  43 ;; (defconst pi       3.14159265358979323846264338327
  44 ;;  "The value of Pi (3.14159265358979323846264338327...)")
  45
  46 (defconst degrees-to-radians (/ pi 180.0)
  47   "Degrees to radian conversion constant")
  48 (defconst radians-to-degrees (/ 180.0 pi)
  49   "Radian to degree conversion constant")
  50
  51 ;; these expand to a single multiply by a float when byte compiled
  52
  53 (defmacro degrees-to-radians (x)
  54   "Convert ARG from degrees to radians."
  55   (list '* (/ pi 180.0) x))
  56 (defmacro radians-to-degrees (x)
  57   "Convert ARG from radians to degrees."
  58   (list '* (/ 180.0 pi) x))
  59
  60 (provide 'lisp-float-type)
  61
  62 ;;; float-sup.el ends here