lisp/emacs-lisp/float-sup.el

   1 ;;; float-sup.el --- define some constants useful for floating point numbers.
   2
   3 ;; Copyright (C) 1985-1987, 2001-2012  Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: internal
   7 ;; Package: emacs
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 ;; Provide an easy hook to tell if we are running with floats or not.
  29 ;; Define pi and e via math-lib calls (much less prone to killer typos).
  30 (defconst float-pi (* 4 (atan 1)) "The value of Pi (3.1415926...).")
  31 (progn
  32   ;; Simulate a defconst that doesn't declare the variable dynamically bound.
  33   (setq-default pi float-pi)
  34   (put 'pi 'variable-documentation
  35        "Obsolete since Emacs-23.3.  Use `float-pi' instead.")
  36   (put 'pi 'risky-local-variable t)
  37   (push 'pi current-load-list))
  38
  39 (defconst float-e (exp 1) "The value of e (2.7182818...).")
  40
  41 (defconst degrees-to-radians (/ float-pi 180.0)
  42   "Degrees to radian conversion constant.")
  43 (defconst radians-to-degrees (/ 180.0 float-pi)
  44   "Radian to degree conversion constant.")
  45
  46 ;; These expand to a single multiply by a float when byte compiled.
  47
  48 (defmacro degrees-to-radians (x)
  49   "Convert X from degrees to radians."
  50   (list '* degrees-to-radians x))
  51 (defmacro radians-to-degrees (x)
  52   "Convert X from radians to degrees."
  53   (list '* radians-to-degrees x))
  54
  55 (provide 'lisp-float-type)
  56
  57 ;;; float-sup.el ends here