;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Software License Agreement (BSD License)
;; 
  Copyright ( c ) 2008 , Willow Garage , Inc.
;; All rights reserved.
;;
;; Redistribution and use in source and binary forms, with 
;; or without modification, are permitted provided that the 
;; following conditions are met:
;;
;;  * Redistributions of source code must retain the above 
;;    copyright notice, this list of conditions and the 
;;    following disclaimer.
;;  * Redistributions in binary form must reproduce the 
;;    above copyright notice, this list of conditions and 
;;    the following disclaimer in the documentation and/or 
;;    other materials provided with the distribution.
   * Neither the name of Willow Garage , Inc. nor the names
;;    of its contributors may be used to endorse or promote 
;;    products derived from this software without specific 
;;    prior written permission.
;; 
;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
  CONTRIBUTORS " AS IS " AND ANY EXPRESS OR 
;; WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 
;; PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
  COPYRIGHT OWNER OR     ANY DIRECT ,
  INDIRECT , INCIDENTAL , SPECIAL , EXEMPLARY , OR
;; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES ; LOSS OF USE ,
  DATA , OR PROFITS ; OR BUSINESS INTERRUPTION ) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY , WHETHER IN
;; CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
;; OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 
;; DAMAGE.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defpackage :roslisp-extended-reals
  (:use :cl)
  (:export
   :infty :-infty
   :ext+ :ext- :extmax))


(in-package :roslisp-extended-reals)

;(declaim (inline ext+ ext- ext>))
(defun ext+ (&rest args)
  (reduce 'add-ext args))

(defun ext- (a &rest args)
  (if args
    (reduce 'subtract (cons a args))
    (negate a)))

(defun extmax (&rest args)
  (when args
    (let ((m '-infty))
      (dolist (x args m)
        (when (ext> x m)
          (setf m x))))))

(defun ext> (a b)
  (cond
    ((eql a 'infty) (not (eql b 'infty)))
    ((eql b '-infty) (not (eql a '-infty)))
    ((and (numberp a) (numberp b)) (> a b))))
    



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  Internal
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;(declaim (inline subtract negate))

(defun add-ext (a b)
  (cond ((symbolp a)
          (cond ((numberp b) a)
                ((eq a b) a)
                (t (assert nil nil "Can't add infty and -infty"))))
        ((symbolp b) b)
        (t (+ a b))))

(defun subtract (a b)
  (cond ((symbolp a)
          (cond ((numberp b) a)
                ((eq a b) (assert nil nil "Can't subtract infty or -infty from themselves."))
                (t a)))
        ((eql b 'infty) '-infty)
        ((eql b '-infty) 'infty)
        (t (- a b))))
	 

(defun negate (a)
  (case a
    (infty '-infty)
    (-infty 'infty)
    (otherwise (- a))))
  

 Software License Agreement (BSD License)
 
 All rights reserved.

 Redistribution and use in source and binary forms, with 
 or without modification, are permitted provided that the 
 following conditions are met:

  * Redistributions of source code must retain the above 
    copyright notice, this list of conditions and the 
    following disclaimer.
  * Redistributions in binary form must reproduce the 
    above copyright notice, this list of conditions and 
    the following disclaimer in the documentation and/or 
    other materials provided with the distribution.
    of its contributors may be used to endorse or promote 
    products derived from this software without specific 
    prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 
 PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 LOSS OF USE ,
 OR BUSINESS INTERRUPTION ) HOWEVER
 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 
 DAMAGE.

(declaim (inline ext+ ext- ext>))


(declaim (inline subtract negate))
  Copyright ( c ) 2008 , Willow Garage , Inc.
   * Neither the name of Willow Garage , Inc. nor the names
  CONTRIBUTORS " AS IS " AND ANY EXPRESS OR 
  COPYRIGHT OWNER OR     ANY DIRECT ,
  INDIRECT , INCIDENTAL , SPECIAL , EXEMPLARY , OR
  CAUSED AND ON ANY THEORY OF LIABILITY , WHETHER IN

(defpackage :roslisp-extended-reals
  (:use :cl)
  (:export
   :infty :-infty
   :ext+ :ext- :extmax))


(in-package :roslisp-extended-reals)

(defun ext+ (&rest args)
  (reduce 'add-ext args))

(defun ext- (a &rest args)
  (if args
    (reduce 'subtract (cons a args))
    (negate a)))

(defun extmax (&rest args)
  (when args
    (let ((m '-infty))
      (dolist (x args m)
        (when (ext> x m)
          (setf m x))))))

(defun ext> (a b)
  (cond
    ((eql a 'infty) (not (eql b 'infty)))
    ((eql b '-infty) (not (eql a '-infty)))
    ((and (numberp a) (numberp b)) (> a b))))
    



  Internal


(defun add-ext (a b)
  (cond ((symbolp a)
          (cond ((numberp b) a)
                ((eq a b) a)
                (t (assert nil nil "Can't add infty and -infty"))))
        ((symbolp b) b)
        (t (+ a b))))

(defun subtract (a b)
  (cond ((symbolp a)
          (cond ((numberp b) a)
                ((eq a b) (assert nil nil "Can't subtract infty or -infty from themselves."))
                (t a)))
        ((eql b 'infty) '-infty)
        ((eql b '-infty) 'infty)
        (t (- a b))))
	 

(defun negate (a)
  (case a
    (infty '-infty)
    (-infty 'infty)
    (otherwise (- a))))
  