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source: branches/f4grobner/.junk/term.lisp@ 4023

Last change on this file since 4023 was 3488, checked in by Marek Rychlik, 9 years ago
File size: 4.4 KB
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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)
[3219]24 (:export "TERM")
[2702]25 (:documentation "This package implements class TERM. A term is a
26product of a scalar and powers of some variables, such as
275*X^2*Y^3. The part of the term without the coefficient is a monomial
28X^2*Y^3, which is represented by class MONOM, provided by the :MONOM
29package. In this implementation, a TERM specializes MONOL. Also, a
30monomial can be considered a TERM whose coefficient is the unit
31element (1) of the underlying ring. The generic method CHANGE-CLASS
32can be used to convert between a MONOM and a TERM, observing this
[2703]33convention."))
[78]34
[420]35(in-package :term)
36
[1926]37(proclaim '(optimize (speed 3) (space 0) (safety 0) (debug 0)))
38
[3287]39;; NOTE: Since term does not have slots of its own,
40;; INITIALIZE-INSTANCE is not called by MAKE-INSTANCE.
[3132]41(defclass term (monom scalar)
[3140]42 ()
[3142]43 (:documentation "Implements a term, i.e. a product of a scalar
[2704]44and powers of some variables, such as 5*X^2*Y^3."))
[766]45
[3211]46(defmethod print-object ((self term) stream)
47 (print-unreadable-object (self stream :type t :identity t)
[3316]48 (with-accessors ((exponents monom-exponents)
[3215]49 (coeff scalar-coeff))
50 self
[3316]51 (format stream "EXPONENTS=~A COEFF=~A"
[3436]52 exponents coeff))))
[3211]53
54
[3151]55(defmethod r-equalp ((term1 term) (term2 term))
[3277]56 (when (r-equalp (scalar-coeff term1) (scalar-coeff term2))
57 (call-next-method)))
[3151]58
[3195]59(defmethod update-instance-for-different-class :after ((old monom) (new scalar) &key)
[3194]60 (setf (scalar-coeff new) 1))
[3164]61
[2946]62(defmethod multiply-by :before ((self term) (other term))
[2833]63 "Destructively multiply terms SELF and OTHER and store the result into SELF.
[2805]64It returns SELF."
[3143]65 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other))))
[2477]66
[3031]67(defmethod left-tensor-product-by ((self term) (other term))
[3143]68 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other)))
[3031]69 (call-next-method))
[3027]70
[3038]71(defmethod right-tensor-product-by ((self term) (other term))
[3143]72 (setf (scalar-coeff self) (multiply-by (scalar-coeff self) (scalar-coeff other)))
[3038]73 (call-next-method))
74
[3059]75(defmethod left-tensor-product-by ((self term) (other monom))
76 (call-next-method))
77
78(defmethod right-tensor-product-by ((self term) (other monom))
79 (call-next-method))
80
[2832]81(defmethod divide-by ((self term) (other term))
[2833]82 "Destructively divide term SELF by OTHER and store the result into SELF.
[2832]83It returns SELF."
[3143]84 (setf (scalar-coeff self) (divide-by (scalar-coeff self) (scalar-coeff other)))
[2832]85 (call-next-method))
86
[2685]87(defmethod unary-minus ((self term))
[3135]88 (setf (scalar-coeff self) (unary-minus (scalar-coeff self)))
[2685]89 self)
90
[2938]91(defmethod r* ((term1 term) (term2 term))
92 "Non-destructively multiply TERM1 by TERM2."
[2967]93 (multiply-by (copy-instance term1) (copy-instance term2)))
[2938]94
[3436]95(defmethod r* ((term1 number) (term2 monom))
96 "Non-destructively multiply TERM1 by TERM2."
97 (r* term1 (change-class (copy-instance term2) 'term)))
98
99(defmethod r* ((term1 number) (term2 term))
100 "Non-destructively multiply TERM1 by TERM2."
101 (setf (scalar-coeff term2)
102 (r* term1 (scalar-coeff term2)))
103 term2)
104
[2942]105(defmethod r-zerop ((self term))
[3135]106 (r-zerop (scalar-coeff self)))
[2938]107
[2352]108#|
[1147]109
110(defun term->cons (term)
[1154]111 "A human-readable representation of a term as a cons (MONOM . COEFF)."
[1902]112 (declare (type term term))
[3135]113 (cons (monom->list (term-monom term)) (scalar-coeff term)))
[1147]114
[2288]115|#
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