guile/module/scheme/inexact.scm

;;; R7RS compatibility libraries
;;; Copyright (C) 2019 Free Software Foundation, Inc.
;;;
;;; This library is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this program.  If not, see
;;; <http://www.gnu.org/licenses/>.

;;; Based on code from https://gitlab.com/akku/akku-scm, written
;;; 2018-2019 by Göran Weinholt <goran@weinholt.se>, as well as
;;; https://github.com/okuoku/yuni, written 2014-2018 by OKUMURA Yuki
;;; <mjt@cltn.org>.  This code was originally released under the
;;; following terms:
;;;
;;;     To the extent possible under law, the author(s) have dedicated
;;;     all copyright and related and neighboring rights to this
;;;     software to the public domain worldwide. This software is
;;;     distributed without any warranty.
;;;
;;;     See <http://creativecommons.org/publicdomain/zero/1.0/>, for a
;;;     copy of the CC0 Public Domain Dedication.

(define-module (scheme inexact)
  #:re-export ((exact->inexact . inexact)
               (inexact->exact . exact)
               acos asin atan cos exp sin sqrt tan)
  #:export ((r7:finite? . finite?)
            (r7:infinite? . infinite?)
            (r7:nan? . nan?)
            (r7:log . log)))

(define (r7:finite? z)
  (if (complex? z)
      (and (finite? (real-part z))
           (finite? (imag-part z)))
      (finite? z)))

(define (r7:infinite? z)
  (if (complex? z)
      (or (inf? (real-part z))
          (inf? (imag-part z)))
      (inf? z)))

(define (r7:nan? z)
  (if (complex? z)
      (or (nan? (real-part z))
          (nan? (imag-part z)))
      (nan? z)))

(define r7:log
  (case-lambda
   ((x) (log x))
   ((x y) (/ (log x) (log y)))))