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source: branches/f4grobner/order-mk.lisp@ 237

Last change on this file since 237 was 190, 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
[190]22(in-package :ngrobner)
[79]23
24;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
25;;
26;; Order making functions
27;;
28;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
29
30(defvar *monomial-order* #'lex>
31 "Default order for monomial comparisons")
32
33(defmacro monomial-order (x y)
34 `(funcall *monomial-order* ,x ,y))
35
36(defun reverse-monomial-order (x y)
37 (monomial-order y x))
38
39(defvar *primary-elimination-order* #'lex>)
40
41(defvar *secondary-elimination-order* #'lex>)
42
43(defvar *elimination-order* nil
44 "Default elimination order used in elimination-based functions.
45If not NIL, it is assumed to be a proper elimination order. If NIL,
46we will construct an elimination order using the values of
47*PRIMARY-ELIMINATION-ORDER* and *SECONDARY-ELIMINATION-ORDER*.")
48
49(defun elimination-order (k)
50 "Return a predicate which compares monomials according to the
51K-th elimination order. Two variables *PRIMARY-ELIMINATION-ORDER*
52and *SECONDARY-ELIMINATION-ORDER* control the behavior on the first K
53and the remaining variables, respectively."
54 (declare (type fixnum k))
55 #'(lambda (p q &optional (start 0) (end (monom-dimension p)))
56 (declare (type monom p q) (type fixnum start end))
57 (multiple-value-bind (primary equal)
58 (funcall *primary-elimination-order* p q start k)
59 (if equal
60 (funcall *secondary-elimination-order* p q k end)
61 (values primary nil)))))
62
63(defun elimination-order-1 (p q &optional (start 0) (end (monom-dimension p)))
64 "Equivalent to the function returned by the call to (ELIMINATION-ORDER 1)."
65 (declare (type monom p q) (type fixnum start end))
66 (cond
67 ((> (monom-elt p start) (monom-elt q start)) (values t nil))
68 ((< (monom-elt p start) (monom-elt q start)) (values nil nil))
69 (t (funcall *secondary-elimination-order* p q (1+ start) end))))
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