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source: branches/f4grobner/order-mk.lisp@ 417

Last change on this file since 417 was 416, checked in by Marek Rychlik, 9 years ago

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[79]1;;; -*- Mode: Lisp; Package: Maxima; Syntax: Common-Lisp; Base: 10 -*-
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
[413]22(defpackage "ORDER-MK"
23 (:use :cl :order)
24 (:export "MONOMIAL-ORDER"
25 "REVERSE-MONOMIAL-ORDER"
26 "*PRIMARY-ELIMINATION-ORDER*"
27 "*SECONDARY-ELIMINATION-ORDER*"
28 "*ELIMINATION-ORDER*"
29 "ELIMINATION-ORDER"
30 "ELIMINATION-ORDER-1"))
[79]31
32(defvar *monomial-order* #'lex>
[414]33 "Default order for monomial comparisons. This global variable holds
34the order which is in effect when performing polynomial
35arithmetic. The global order is called by the macro MONOMIAL-ORDER,
36which is somewhat more elegant than FUNCALL.")
[79]37
38(defmacro monomial-order (x y)
[415]39 "Calls the global monomial order function, held by *MONOMIAL-ORDER*."
[79]40 `(funcall *monomial-order* ,x ,y))
41
[416]42(defmacro reverse-monomial-order (x y)
[415]43 "Calls the inverse monomial order to the global monomial order function,
44held by *MONOMIAL-ORDER*."
[416]45 `(monomial-order ,y ,x))
[79]46
47(defvar *primary-elimination-order* #'lex>)
48
49(defvar *secondary-elimination-order* #'lex>)
50
51(defvar *elimination-order* nil
52 "Default elimination order used in elimination-based functions.
53If not NIL, it is assumed to be a proper elimination order. If NIL,
54we will construct an elimination order using the values of
55*PRIMARY-ELIMINATION-ORDER* and *SECONDARY-ELIMINATION-ORDER*.")
56
[414]57;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
58;;
59;; Order making functions
60;;
61;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
62
[79]63(defun elimination-order (k)
64 "Return a predicate which compares monomials according to the
65K-th elimination order. Two variables *PRIMARY-ELIMINATION-ORDER*
66and *SECONDARY-ELIMINATION-ORDER* control the behavior on the first K
67and the remaining variables, respectively."
68 (declare (type fixnum k))
69 #'(lambda (p q &optional (start 0) (end (monom-dimension p)))
70 (declare (type monom p q) (type fixnum start end))
71 (multiple-value-bind (primary equal)
72 (funcall *primary-elimination-order* p q start k)
73 (if equal
74 (funcall *secondary-elimination-order* p q k end)
75 (values primary nil)))))
76
77(defun elimination-order-1 (p q &optional (start 0) (end (monom-dimension p)))
78 "Equivalent to the function returned by the call to (ELIMINATION-ORDER 1)."
79 (declare (type monom p q) (type fixnum start end))
80 (cond
81 ((> (monom-elt p start) (monom-elt q start)) (values t nil))
82 ((< (monom-elt p start) (monom-elt q start)) (values nil nil))
83 (t (funcall *secondary-elimination-order* p q (1+ start) end))))
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