1 | #|
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2 | $Id: term.lisp,v 1.4 2009/01/22 04:08:39 marek Exp $
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3 | *--------------------------------------------------------------------------*
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4 | | Copyright (C) 1994, Marek Rychlik (e-mail: rychlik@math.arizona.edu) |
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5 | | Department of Mathematics, University of Arizona, Tucson, AZ 85721 |
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6 | | |
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7 | | Everyone is permitted to copy, distribute and modify the code in this |
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8 | | directory, as long as this copyright note is preserved verbatim. |
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9 | *--------------------------------------------------------------------------*
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10 | |#
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11 |
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12 | (defpackage "TERM"
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13 | (:use "MONOM" "COEFFICIENT-RING" "COMMON-LISP")
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14 | (:export term-divides-p term* term/ term-coefficient term-monom monom-times-term))
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15 |
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16 | (in-package "TERM")
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17 |
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18 | (proclaim '(optimize (speed 3) (space 0) (safety 0) (debug 0)))
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19 |
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20 | ;;----------------------------------------------------------------
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21 | ;; Basic operations on terms
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22 | ;;----------------------------------------------------------------
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23 | ;; THE REPRESENTATION: Terms are cons cells consisting
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24 | ;; of a monom and coefficient
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25 | ;;
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26 | ;; term: (monom . coefficient)
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27 | ;;
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28 | ;;----------------------------------------------------------------
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29 | ;; EXAMPLES: Suppose that variables are x and y. Then
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30 | ;; Term 3*x*y^2 ---> ((1 2) . 3)
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31 | ;;----------------------------------------------------------------
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32 |
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33 | ;; Multiplication of terms
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34 | (defun term* (term1 term2 &optional (ring *coefficient-ring*))
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35 | (cons
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36 | (monom* (car term1) (car term2))
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37 | (funcall (ring-* ring) (cdr term1) (cdr term2))))
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38 |
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39 | ;;;; Division of terms
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40 | (defun term/ (term1 term2 &optional (ring *coefficient-ring*))
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41 | (cons
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42 | (monom/ (car term1) (car term2))
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43 | (funcall (ring-/ ring) (cdr term1) (cdr term2))))
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44 |
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45 | ;; Multiply monomial by term
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46 | (defun monom-times-term (m term)
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47 | (cons (monom* m (car term)) (cdr term)))
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48 |
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49 | ;; Whether a term divides another term
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50 | (defun term-divides-p (term1 term2)
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51 | (monom-divides-p (car term1) (car term2)))
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52 |
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53 | ;; Accessor functions
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54 | (defmacro term-monom (term) `(car ,term))
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55 | (defmacro term-coefficient (term) `(cdr ,term))
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56 |
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57 | ;; Setf methods
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58 | (defsetf term-monom (term) (monom)
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59 | `(setf (car ,term) ,monom))
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60 |
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61 | (defsetf term-coefficient (term) (coefficient)
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62 | `(setf (cdr ,term) ,coefficient))
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63 |
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