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source: branches/f4grobner/order-mk.lisp@ 440

Last change on this file since 440 was 430, checked in by Marek Rychlik, 9 years ago

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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
22(defpackage "ORDER-MK"
23 (:use :cl :order :monomial)
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"))
31
32(in-package :order-mk)
33
34;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
35;;
36;; Some globally-defined variables holding monomial orders
37;; and related macros/functions.
38;;
39;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
40
41(defvar *monomial-order* #'lex>
42 "Default order for monomial comparisons. This global variable holds
43the order which is in effect when performing polynomial
44arithmetic. The global order is called by the macro MONOMIAL-ORDER,
45which is somewhat more elegant than FUNCALL.")
46
47(defmacro monomial-order (x y)
48 "Calls the global monomial order function, held by *MONOMIAL-ORDER*."
49 `(funcall *monomial-order* ,x ,y))
50
51(defmacro reverse-monomial-order (x y)
52 "Calls the inverse monomial order to the global monomial order function,
53held by *MONOMIAL-ORDER*."
54 `(monomial-order ,y ,x))
55
56(defvar *primary-elimination-order* #'lex>)
57
58(defvar *secondary-elimination-order* #'lex>)
59
60(defvar *elimination-order* nil
61 "Default elimination order used in elimination-based functions.
62If not NIL, it is assumed to be a proper elimination order. If NIL,
63we will construct an elimination order using the values of
64*PRIMARY-ELIMINATION-ORDER* and *SECONDARY-ELIMINATION-ORDER*.")
65
66;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
67;;
68;; Order making functions
69;;
70;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
71
72(defun elimination-order (k)
73 "Return a predicate which compares monomials according to the
74K-th elimination order. Two variables *PRIMARY-ELIMINATION-ORDER*
75and *SECONDARY-ELIMINATION-ORDER* control the behavior on the first K
76and the remaining variables, respectively."
77 (declare (type fixnum k))
78 #'(lambda (p q &optional (start 0) (end (monom-dimension p)))
79 (declare (type monom p q) (type fixnum start end))
80 (multiple-value-bind (primary equal)
81 (funcall *primary-elimination-order* p q start k)
82 (if equal
83 (funcall *secondary-elimination-order* p q k end)
84 (values primary nil)))))
85
86(defun elimination-order-1 (p q &optional (start 0) (end (monom-dimension p)))
87 "Equivalent to the function returned by the call to (ELIMINATION-ORDER 1)."
88 (declare (type monom p q) (type fixnum start end))
89 (cond
90 ((> (monom-elt p start) (monom-elt q start)) (values t nil))
91 ((< (monom-elt p start) (monom-elt q start)) (values nil nil))
92 (t (funcall *secondary-elimination-order* p q (1+ start) end))))
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