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1 | ;;; float-sup.el --- define some constants useful for floating point numbers. |
2 | ||
3 | ;; Copyright (C) 1985, 1986, 1987 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Maintainer: FSF | |
6 | ;; Keywords: internal | |
7 | ||
8 | ;; This file is part of GNU Emacs. | |
9 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation; either version 2, or (at your option) | |
13 | ;; any later version. | |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
24 | ||
25 | ;;; Commentary: | |
26 | ||
27 | ;;; Code: | |
28 | ||
29 | ;; Provide a meaningful error message if we are running on | |
30 | ;; bare (non-float) emacs. | |
31 | ||
32 | (if (fboundp 'atan) | |
33 | nil | |
34 | (error "Floating point was disabled at compile time")) | |
35 | ||
36 | ;; provide an easy hook to tell if we are running with floats or not. | |
37 | ;; define pi and e via math-lib calls. (much less prone to killer typos.) | |
38 | (defconst pi (* 4 (atan 1)) "The value of Pi (3.1415926...).") | |
39 | ;; It's too inconvenient to make `e' a constant because it's used as | |
40 | ;; a temporary variable all the time. | |
41 | (defvar e (exp 1) "The value of e (2.7182818...).") | |
42 | ||
43 | ;; Careful when editing this file ... typos here will be hard to spot. | |
44 | ;; (defconst pi 3.14159265358979323846264338327 | |
45 | ;; "The value of Pi (3.14159265358979323846264338327...)") | |
46 | ||
47 | (defconst degrees-to-radians (/ pi 180.0) | |
48 | "Degrees to radian conversion constant.") | |
49 | (defconst radians-to-degrees (/ 180.0 pi) | |
50 | "Radian to degree conversion constant.") | |
51 | ||
52 | ;; these expand to a single multiply by a float when byte compiled | |
53 | ||
54 | (defmacro degrees-to-radians (x) | |
55 | "Convert ARG from degrees to radians." | |
56 | (list '* (/ pi 180.0) x)) | |
57 | (defmacro radians-to-degrees (x) | |
58 | "Convert ARG from radians to degrees." | |
59 | (list '* (/ 180.0 pi) x)) | |
60 | ||
61 | (provide 'lisp-float-type) | |
62 | ||
ab5796a9 | 63 | ;;; arch-tag: e7837072-a4af-4d08-9953-8a3e755abf9d |
5e046f6d | 64 | ;;; float-sup.el ends here |