| 1 | ;;; -*- Mode: Lisp -*-
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| 2 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 3 | ;;;
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| 4 | ;;; Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>
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| 5 | ;;;
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| 6 | ;;; This program is free software; you can redistribute it and/or modify
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| 7 | ;;; it under the terms of the GNU General Public License as published by
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| 8 | ;;; the Free Software Foundation; either version 2 of the License, or
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| 9 | ;;; (at your option) any later version.
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| 10 | ;;;
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| 11 | ;;; This program is distributed in the hope that it will be useful,
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| 12 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | ;;; GNU General Public License for more details.
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| 15 | ;;;
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| 16 | ;;; You should have received a copy of the GNU General Public License
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| 17 | ;;; along with this program; if not, write to the Free Software
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| 18 | ;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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| 19 | ;;;
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| 20 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 21 |
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| 22 | (in-package "RING")
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| 23 |
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| 24 | (defclass integer-ring (rational-field)
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| 25 | ((value :initarg :value :initform 0 :accessor integer-ring-value :type integer))
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| 26 | (:documentation "An object representing an integer.")
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| 27 | )
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| 28 |
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| 29 | (defmethod print-object ((self integer-ring) stream)
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| 30 | (print-unreadable-object (self stream :type t :identity t)
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| 31 | (with-accessors ((value integer-ring-value))
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| 32 | self
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| 33 | (format stream "VALUE=~A" value))))
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| 34 |
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| 35 | (defmethod shared-initialize :around ((self integer-ring) slot-names
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| 36 | &rest initargs
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| 37 | &key (value nil value-supplied-p))
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| 38 | "Checks the argument VALUE. Calls error if it is not an integer."
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| 39 | (declare (ignore initargs))
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| 40 | (when value-supplied-p
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| 41 | (assert (integerp value) nil "When initializing INTEGER-RING, argument VALUE must be an integer, got ~S." value))
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| 42 | (call-next-method))
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| 43 |
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| 44 |
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| 45 | (defmethod unary-inverse ((self integer-ring))
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| 46 | "Invert SELF, possibly changing class to RATIONAL-FIELD."
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| 47 | (with-slots (value)
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| 48 | self
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| 49 | (case value
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| 50 | (1 self)
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| 51 | (-1 self)
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| 52 | (t
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| 53 | (warn "In UNARY-INVERSE with argument ~S, conversion from INTEGER-RING to RATIONAL-FIELD." self)
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| 54 | (unary-inverse (change-class self 'rational-field))))))
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| 55 |
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| 56 | (defmethod universal-gcd ((self integer-ring) (other integer-ring))
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| 57 | (with-slots (value)
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| 58 | self
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| 59 | (with-slots ((other-value value))
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| 60 | other
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| 61 | (make-instance 'integer-ring :value (gcd value other-value)))))
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| 62 |
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| 63 | (defmethod universal-ezgcd ((object integer-ring) (other integer-ring))
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| 64 | (with-slots (value)
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| 65 | object
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| 66 | (with-slots ((other-value value))
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| 67 | other
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| 68 | (let ((c (gcd value other-value)))
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| 69 | (values (make-instance 'integer-ring :value c)
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| 70 | (make-instance 'integer-ring :value (/ value c))
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| 71 | (make-instance 'integer-ring :value (/ other-value c)))))))
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