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 ;;; Code:
  25
  26 ;; Provide a meaningful error message if we are running on
  27 ;; bare (non-float) emacs.
  28 ;; Can't test for 'floatp since that may be defined by float-imitation
  29 ;; packages like float.el in this very directory.
  30
  31 (if (fboundp 'atan)
  32     nil
  33   (error "Floating point was disabled at compile time"))
  34
  35 ;; provide an easy hook to tell if we are running with floats or not.
  36 ;; define pi and e via math-lib calls. (much less prone to killer typos.)
  37 (defconst pi (* 4 (atan 1)) "The value of Pi (3.1415926...)")
  38 (defconst e (exp 1) "The value of e (2.7182818...)")
  39
  40 ;; Careful when editing this file ... typos here will be hard to spot.
  41 ;; (defconst pi       3.14159265358979323846264338327
  42 ;;  "The value of Pi (3.14159265358979323846264338327...)")
  43
  44 (defconst degrees-to-radians (/ pi 180.0)
  45   "Degrees to radian conversion constant")
  46 (defconst radians-to-degrees (/ 180.0 pi)
  47   "Radian to degree conversion constant")
  48
  49 ;; these expand to a single multiply by a float when byte compiled
  50
  51 (defmacro degrees-to-radians (x)
  52   "Convert ARG from degrees to radians."
  53   (list '* (/ pi 180.0) x))
  54 (defmacro radians-to-degrees (x)
  55   "Convert ARG from radians to degrees."
  56   (list '* (/ 180.0 pi) x))
  57
  58 (provide 'lisp-float-type)
  59
  60 ;;; float-sup.el ends here