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 ;; This file is part of GNU Emacs.
   6
   7 ;; GNU Emacs is free software; you can redistribute it and/or modify
   8 ;; it under the terms of the GNU General Public License as published by
   9 ;; the Free Software Foundation; either version 1, or (at your option)
  10 ;; any later version.
  11
  12 ;; GNU Emacs is distributed in the hope that it will be useful,
  13 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 ;; GNU General Public License for more details.
  16
  17 ;; You should have received a copy of the GNU General Public License
  18 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  19 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21 ;; Provide a meaningful error message if we are running on
  22 ;; bare (non-float) emacs.
  23 ;; Can't test for 'floatp since that may be defined by float-imitation
  24 ;; packages like float.el in this very directory.
  25
  26 (if (fboundp 'atan)
  27     nil
  28   (error "Floating point was disabled at compile time"))
  29
  30 ;; provide an easy hook to tell if we are running with floats or not.
  31 ;; define pi and e via math-lib calls. (much less prone to killer typos.)
  32 (defconst pi (* 4 (atan 1)) "The value of Pi (3.1415926...)")
  33 (defconst e (exp 1) "The value of e (2.7182818...)")
  34
  35 ;; Careful when editing this file ... typos here will be hard to spot.
  36 ;; (defconst pi       3.14159265358979323846264338327
  37 ;;  "The value of Pi (3.14159265358979323846264338327...)")
  38
  39 (defconst degrees-to-radians (/ pi 180.0)
  40   "Degrees to radian conversion constant")
  41 (defconst radians-to-degrees (/ 180.0 pi)
  42   "Radian to degree conversion constant")
  43
  44 ;; these expand to a single multiply by a float when byte compiled
  45
  46 (defmacro degrees-to-radians (x)
  47   "Convert ARG from degrees to radians."
  48   (list '* (/ pi 180.0) x))
  49 (defmacro radians-to-degrees (x)
  50   "Convert ARG from radians to degrees."
  51   (list '* (/ 180.0 pi) x))
  52
  53 (provide 'lisp-float-type)
  54
  55 ;;; float-sup.el ends here