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source: branches/f4grobner/term.lisp@ 3200

Last change on this file since 3200 was 3200, checked in by Marek Rychlik, 9 years ago

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[1201]1;;; -*- Mode: Lisp -*-
[78]2;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
3;;;
4;;; Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>
5;;;
6;;; This program is free software; you can redistribute it and/or modify
7;;; it under the terms of the GNU General Public License as published by
8;;; the Free Software Foundation; either version 2 of the License, or
9;;; (at your option) any later version.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14;;; GNU General Public License for more details.
15;;;
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19;;;
20;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
21
[397]22(defpackage "TERM"
[1605]23 (:use :cl :monom :ring)
[2845]24 (:export "TERM"
25 "MAKE-TERM-VARIABLE"
26 )
[2702]27 (:documentation "This package implements class TERM. A term is a
28product of a scalar and powers of some variables, such as
295*X^2*Y^3. The part of the term without the coefficient is a monomial
30X^2*Y^3, which is represented by class MONOM, provided by the :MONOM
31package. In this implementation, a TERM specializes MONOL. Also, a
32monomial can be considered a TERM whose coefficient is the unit
33element (1) of the underlying ring. The generic method CHANGE-CLASS
34can be used to convert between a MONOM and a TERM, observing this
[2703]35convention."))
[78]36
[420]37(in-package :term)
38
[1926]39(proclaim '(optimize (speed 3) (space 0) (safety 0) (debug 0)))
40
[3132]41(defclass term (monom scalar)
[3140]42 ()
[3176]43 (:default-initargs :dimension 0 :exponents '() :coeff 1)
[3142]44 (:documentation "Implements a term, i.e. a product of a scalar
[2704]45and powers of some variables, such as 5*X^2*Y^3."))
[766]46
[3200]47#|
[2275]48(defmethod print-object ((self term) stream)
[3198]49 (print-unreadable-object (self stream :type t :identity t)
[3199]50 (format stream "DIMENSION=~A EXPONENTS=~A COEFF=~A"
51 (slot-value self 'coeff))))
[3200]52|#
[2275]53
[3151]54(defmethod r-equalp ((term1 term) (term2 term))
55 (and (r-equalp (scalar-coeff term1) (scalar-coeff term2))
[3152]56 (= (monom-dimension term1) (monom-dimension term2))
57 (equalp (monom-exponents term1) (monom-exponents term2))))
[3151]58
59
[3141]60#|
[2339]61(defmethod shared-initialize ((self term) slot-names
62 &rest
[2395]63 initargs
[2339]64 &key
[2377]65 coeff
66 &allow-other-keys)
[2395]67 (declare (ignore initargs))
[2385]68 (if (eq slot-names t) (setf slot-names '(coeff)))
[2378]69 (dolist (slot-name slot-names)
70 (case slot-name
71 (coeff
[2391]72 (setf (slot-value self 'coeff) coeff)))))
[3141]73|#
[2342]74
[3195]75(defmethod update-instance-for-different-class :after ((old monom) (new scalar) &key)
[3194]76 (setf (scalar-coeff new) 1))
[3164]77
[2288]78#|
[2189]79(defun make-term-variable (nvars pos
[2021]80 &optional
81 (power 1)
[2189]82 (coeff 1))
[400]83 "Construct a term in the polynomial ring RING[X[0],X[1],X[2],...X[NVARS-1]]
[399]84over the ring RING which represents a single variable. It assumes
85number of variables NVARS and the variable is at position
86POS. Optionally, the variable may appear raised to power POWER.
87Optionally, the term may appear with an arbitrary coefficient, which
88defaults to the unit of the RING."
[2189]89 (declare (type fixnum nvars pos))
[1959]90 (make-term :monom (make-monom-variable nvars pos power)
91 :coeff coeff))
[51]92
[2352]93|#
94
[2946]95(defmethod multiply-by :before ((self term) (other term))
[2833]96 "Destructively multiply terms SELF and OTHER and store the result into SELF.
[2805]97It returns SELF."
[3143]98 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other))))
[2477]99
[3031]100(defmethod left-tensor-product-by ((self term) (other term))
[3143]101 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other)))
[3031]102 (call-next-method))
[3027]103
[3038]104(defmethod right-tensor-product-by ((self term) (other term))
[3143]105 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other)))
[3038]106 (call-next-method))
107
[3059]108(defmethod left-tensor-product-by ((self term) (other monom))
109 (call-next-method))
110
111(defmethod right-tensor-product-by ((self term) (other monom))
112 (call-next-method))
113
[2832]114(defmethod divide-by ((self term) (other term))
[2833]115 "Destructively divide term SELF by OTHER and store the result into SELF.
[2832]116It returns SELF."
[3143]117 (setf (scalar-coeff self) (divide-by (scalar-coeff self) (scalar-coeff other)))
[2832]118 (call-next-method))
119
[2685]120(defmethod unary-minus ((self term))
[3135]121 (setf (scalar-coeff self) (unary-minus (scalar-coeff self)))
[2685]122 self)
123
[2938]124(defmethod r* ((term1 term) (term2 term))
125 "Non-destructively multiply TERM1 by TERM2."
[2967]126 (multiply-by (copy-instance term1) (copy-instance term2)))
[2938]127
[2942]128(defmethod r-zerop ((self term))
[3135]129 (r-zerop (scalar-coeff self)))
[2938]130
[2352]131#|
[1147]132
133(defun term->cons (term)
[1154]134 "A human-readable representation of a term as a cons (MONOM . COEFF)."
[1902]135 (declare (type term term))
[3135]136 (cons (monom->list (term-monom term)) (scalar-coeff term)))
[1147]137
[2288]138|#
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