| [79] | 1 | ;;; -*- Mode: Lisp; Package: Maxima; Syntax: Common-Lisp; Base: 10 -*-
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| 2 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 3 | ;;;
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| 4 | ;;; Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>
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| 5 | ;;;
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| 6 | ;;; This program is free software; you can redistribute it and/or modify
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| 7 | ;;; it under the terms of the GNU General Public License as published by
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| 8 | ;;; the Free Software Foundation; either version 2 of the License, or
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| 9 | ;;; (at your option) any later version.
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| 10 | ;;;
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| 11 | ;;; This program is distributed in the hope that it will be useful,
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| 12 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | ;;; GNU General Public License for more details.
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| 15 | ;;;
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| 16 | ;;; You should have received a copy of the GNU General Public License
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| 17 | ;;; along with this program; if not, write to the Free Software
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| 18 | ;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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| 19 | ;;;
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| 20 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 21 |
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| [141] | 22 | (in-package :grobner)
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| [79] | 23 |
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| 24 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 25 | ;;
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| 26 | ;; Order making functions
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| 27 | ;;
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| 28 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 29 |
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| 30 | (defvar *monomial-order* #'lex>
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| 31 | "Default order for monomial comparisons")
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| 32 |
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| 33 | (defmacro monomial-order (x y)
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| 34 | `(funcall *monomial-order* ,x ,y))
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| 35 |
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| 36 | (defun reverse-monomial-order (x y)
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| 37 | (monomial-order y x))
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| 38 |
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| 39 | (defvar *primary-elimination-order* #'lex>)
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| 40 |
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| 41 | (defvar *secondary-elimination-order* #'lex>)
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| 42 |
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| 43 | (defvar *elimination-order* nil
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| 44 | "Default elimination order used in elimination-based functions.
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| 45 | If not NIL, it is assumed to be a proper elimination order. If NIL,
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| 46 | we will construct an elimination order using the values of
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| 47 | *PRIMARY-ELIMINATION-ORDER* and *SECONDARY-ELIMINATION-ORDER*.")
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| 48 |
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| 49 | (defun elimination-order (k)
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| 50 | "Return a predicate which compares monomials according to the
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| 51 | K-th elimination order. Two variables *PRIMARY-ELIMINATION-ORDER*
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| 52 | and *SECONDARY-ELIMINATION-ORDER* control the behavior on the first K
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| 53 | and the remaining variables, respectively."
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| 54 | (declare (type fixnum k))
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| 55 | #'(lambda (p q &optional (start 0) (end (monom-dimension p)))
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| 56 | (declare (type monom p q) (type fixnum start end))
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| 57 | (multiple-value-bind (primary equal)
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| 58 | (funcall *primary-elimination-order* p q start k)
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| 59 | (if equal
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| 60 | (funcall *secondary-elimination-order* p q k end)
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| 61 | (values primary nil)))))
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| 62 |
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| 63 | (defun elimination-order-1 (p q &optional (start 0) (end (monom-dimension p)))
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| 64 | "Equivalent to the function returned by the call to (ELIMINATION-ORDER 1)."
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| 65 | (declare (type monom p q) (type fixnum start end))
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| 66 | (cond
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| 67 | ((> (monom-elt p start) (monom-elt q start)) (values t nil))
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| 68 | ((< (monom-elt p start) (monom-elt q start)) (values nil nil))
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| 69 | (t (funcall *secondary-elimination-order* p q (1+ start) end))))
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