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source: branches/f4grobner/polynomial.lisp@ 1496

Last change on this file since 1496 was 1495, checked in by Marek Rychlik, 10 years ago

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[1201]1;;; -*- Mode: Lisp -*-
[77]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
[431]23(defpackage "POLYNOMIAL"
[1072]24 (:use :cl :ring :ring-and-order :monomial :order :term :termlist :infix)
[432]25 (:export "POLY"
26 "POLY-TERMLIST"
27 "POLY-SUGAR"
[1218]28 "POLY-RESET-SUGAR"
[432]29 "POLY-LT"
[433]30 "MAKE-POLY-FROM-TERMLIST"
31 "MAKE-POLY-ZERO"
32 "MAKE-VARIABLE"
33 "POLY-UNIT"
34 "POLY-LM"
35 "POLY-SECOND-LM"
36 "POLY-SECOND-LT"
37 "POLY-LC"
38 "POLY-SECOND-LC"
39 "POLY-ZEROP"
[458]40 "POLY-LENGTH"
[433]41 "SCALAR-TIMES-POLY"
42 "SCALAR-TIMES-POLY-1"
43 "MONOM-TIMES-POLY"
44 "TERM-TIMES-POLY"
45 "POLY-ADD"
46 "POLY-SUB"
47 "POLY-UMINUS"
48 "POLY-MUL"
49 "POLY-EXPT"
50 "POLY-APPEND"
51 "POLY-NREVERSE"
[1266]52 "POLY-REVERSE"
[433]53 "POLY-CONTRACT"
54 "POLY-EXTEND"
55 "POLY-ADD-VARIABLES"
56 "POLY-LIST-ADD-VARIABLES"
57 "POLY-STANDARD-EXTENSION"
58 "SATURATION-EXTENSION"
59 "POLYSATURATION-EXTENSION"
60 "SATURATION-EXTENSION-1"
61 "COERCE-COEFF"
62 "POLY-EVAL"
[1134]63 "POLY-EVAL-SCALAR"
[433]64 "SPOLY"
65 "POLY-PRIMITIVE-PART"
66 "POLY-CONTENT"
[1085]67 "READ-INFIX-FORM"
[1093]68 "READ-POLY"
[1104]69 "STRING->POLY"
[1159]70 "POLY->ALIST"
71 "STRING->ALIST"
[1441]72 "POLY-EQUAL-NO-SUGAR-P"
[432]73 ))
[143]74
[431]75(in-package :polynomial)
76
[52]77;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
78;;
79;; Polynomials
80;;
81;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
82
83(defstruct (poly
84 ;;
85 ;; BOA constructor, by default constructs zero polynomial
86 (:constructor make-poly-from-termlist (termlist &optional (sugar (termlist-sugar termlist))))
87 (:constructor make-poly-zero (&aux (termlist nil) (sugar -1)))
88 ;; Constructor of polynomials representing a variable
89 (:constructor make-variable (ring nvars pos &optional (power 1)
[53]90 &aux
91 (termlist (list
92 (make-term-variable ring nvars pos power)))
93 (sugar power)))
94 (:constructor poly-unit (ring dimension
95 &aux
96 (termlist (termlist-unit ring dimension))
97 (sugar 0))))
[52]98 (termlist nil :type list)
99 (sugar -1 :type fixnum))
100
101;; Leading term
102(defmacro poly-lt (p) `(car (poly-termlist ,p)))
103
104;; Second term
105(defmacro poly-second-lt (p) `(cadar (poly-termlist ,p)))
106
107;; Leading monomial
108(defun poly-lm (p) (term-monom (poly-lt p)))
109
110;; Second monomial
111(defun poly-second-lm (p) (term-monom (poly-second-lt p)))
112
113;; Leading coefficient
114(defun poly-lc (p) (term-coeff (poly-lt p)))
115
116;; Second coefficient
117(defun poly-second-lc (p) (term-coeff (poly-second-lt p)))
118
119;; Testing for a zero polynomial
120(defun poly-zerop (p) (null (poly-termlist p)))
121
122;; The number of terms
123(defun poly-length (p) (length (poly-termlist p)))
124
[1215]125(defun poly-reset-sugar (p)
[1217]126 "(Re)sets the sugar of a polynomial P to the sugar of (POLY-TERMLIST P).
127Thus, the sugar is set to the maximum sugar of all monomials of P, or -1
128if P is a zero polynomial."
[1215]129 (declare (type poly p))
[1216]130 (setf (poly-sugar p) (termlist-sugar (poly-termlist p)))
131 p)
[1215]132
[52]133(defun scalar-times-poly (ring c p)
[1214]134 "The scalar product of scalar C by a polynomial P. The sugar of the
135original polynomial becomes the sugar of the result."
[1215]136 (declare (type ring ring) (type poly p))
[52]137 (make-poly-from-termlist (scalar-times-termlist ring c (poly-termlist p)) (poly-sugar p)))
138
139(defun scalar-times-poly-1 (ring c p)
[1213]140 "The scalar product of scalar C by a polynomial P, omitting the head term. The sugar of the
141original polynomial becomes the sugar of the result."
[1215]142 (declare (type ring ring) (type poly p))
[52]143 (make-poly-from-termlist (scalar-times-termlist ring c (cdr (poly-termlist p))) (poly-sugar p)))
[53]144
[52]145(defun monom-times-poly (m p)
[1215]146 (declare (type poly p))
[980]147 (make-poly-from-termlist
148 (monom-times-termlist m (poly-termlist p))
149 (+ (poly-sugar p) (monom-sugar m))))
[52]150
151(defun term-times-poly (ring term p)
[982]152 (declare (type ring ring) (type term term) (type poly p))
[979]153 (make-poly-from-termlist
154 (term-times-termlist ring term (poly-termlist p))
155 (+ (poly-sugar p) (term-sugar term))))
[52]156
[978]157(defun poly-add (ring-and-order p q)
[980]158 (declare (type ring-and-order ring-and-order) (type poly p q))
[978]159 (make-poly-from-termlist
160 (termlist-add ring-and-order
161 (poly-termlist p)
162 (poly-termlist q))
163 (max (poly-sugar p) (poly-sugar q))))
[52]164
[980]165(defun poly-sub (ring-and-order p q)
166 (declare (type ring-and-order ring-and-order) (type poly p q))
167 (make-poly-from-termlist
[990]168 (termlist-sub ring-and-order (poly-termlist p) (poly-termlist q))
[980]169 (max (poly-sugar p) (poly-sugar q))))
[52]170
171(defun poly-uminus (ring p)
[983]172 (declare (type ring ring) (type poly p))
173 (make-poly-from-termlist
174 (termlist-uminus ring (poly-termlist p))
175 (poly-sugar p)))
[52]176
[984]177(defun poly-mul (ring-and-order p q)
178 (declare (type ring-and-order ring-and-order) (type poly p q))
179 (make-poly-from-termlist
[991]180 (termlist-mul ring-and-order (poly-termlist p) (poly-termlist q))
[984]181 (+ (poly-sugar p) (poly-sugar q))))
[52]182
[985]183(defun poly-expt (ring-and-order p n)
184 (declare (type ring-and-order ring-and-order) (type poly p))
[992]185 (make-poly-from-termlist (termlist-expt ring-and-order (poly-termlist p) n) (* n (poly-sugar p))))
[52]186
187(defun poly-append (&rest plist)
188 (make-poly-from-termlist (apply #'append (mapcar #'poly-termlist plist))
[53]189 (apply #'max (mapcar #'poly-sugar plist))))
[52]190
191(defun poly-nreverse (p)
[1268]192 "Destructively reverse the order of terms in polynomial P. Returns P"
[986]193 (declare (type poly p))
[52]194 (setf (poly-termlist p) (nreverse (poly-termlist p)))
195 p)
196
[1265]197(defun poly-reverse (p)
[1268]198 "Returns a copy of the polynomial P with terms in reverse order."
[1265]199 (declare (type poly p))
200 (make-poly-from-termlist (reverse (poly-termlist p))
201 (poly-sugar p)))
202
203
[52]204(defun poly-contract (p &optional (k 1))
[986]205 (declare (type poly p))
[52]206 (make-poly-from-termlist (termlist-contract (poly-termlist p) k)
[53]207 (poly-sugar p)))
[52]208
[973]209(defun poly-extend (p &optional (m (make-monom :dimension 1)))
[987]210 (declare (type poly p))
[52]211 (make-poly-from-termlist
212 (termlist-extend (poly-termlist p) m)
213 (+ (poly-sugar p) (monom-sugar m))))
214
215(defun poly-add-variables (p k)
[988]216 (declare (type poly p))
[52]217 (setf (poly-termlist p) (termlist-add-variables (poly-termlist p) k))
218 p)
219
220(defun poly-list-add-variables (plist k)
221 (mapcar #'(lambda (p) (poly-add-variables p k)) plist))
222
223(defun poly-standard-extension (plist &aux (k (length plist)))
224 "Calculate [U1*P1,U2*P2,...,UK*PK], where PLIST=[P1,P2,...,PK]."
225 (declare (list plist) (fixnum k))
226 (labels ((incf-power (g i)
227 (dolist (x (poly-termlist g))
228 (incf (monom-elt (term-monom x) i)))
229 (incf (poly-sugar g))))
230 (setf plist (poly-list-add-variables plist k))
231 (dotimes (i k plist)
232 (incf-power (nth i plist) i))))
233
[1473]234(defun saturation-extension (ring f plist
235 &aux
236 (k (length plist))
[1474]237 (d (monom-dimension (poly-lm (car plist))))
238 f-x plist-x)
[52]239 "Calculate [F, U1*P1-1,U2*P2-1,...,UK*PK-1], where PLIST=[P1,P2,...,PK]."
[1474]240 (setf f-x (poly-list-add-variables f k)
241 plist-x (mapcar #'(lambda (x)
242 (setf (poly-termlist x) (nconc (poly-termlist x)
243 (list (make-term (make-monom :dimension d)
244 (funcall (ring-uminus ring) (funcall (ring-unit ring)))))))
245 x)
246 (poly-standard-extension plist)))
247 (append f-x plist-x))
[52]248
249
[1475]250(defun polysaturation-extension (ring f plist
251 &aux
252 (k (length plist))
[1476]253 (d (+ k (monom-dimension (poly-lm (car plist)))))
[1494]254 ;; Add k variables to f
[1493]255 (f (poly-list-add-variables f k))
[1495]256 ;; Set PLIST to [U1*P1,U2*P2,...,UK*PK]
[1493]257 (plist (apply #'poly-append (poly-standard-extension plist))))
[52]258 "Calculate [F, U1*P1+U2*P2+...+UK*PK-1], where PLIST=[P1,P2,...,PK]."
[1493]259 ;; Add -1 as the last term
260 (setf (cdr (last (poly-termlist plist)))
261 (list (make-term (make-monom :dimension d)
262 (funcall (ring-uminus ring) (funcall (ring-unit ring))))))
263 (append f (list plist)))
[52]264
[1477]265(defun saturation-extension-1 (ring f p)
266 (polysaturation-extension ring f (list p)))
[53]267
268;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
269;;
270;; Evaluation of polynomial (prefix) expressions
271;;
272;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
273
274(defun coerce-coeff (ring expr vars)
275 "Coerce an element of the coefficient ring to a constant polynomial."
276 ;; Modular arithmetic handler by rat
[975]277 (make-poly-from-termlist (list (make-term (make-monom :dimension (length vars))
[53]278 (funcall (ring-parse ring) expr)))
279 0))
280
[1046]281(defun poly-eval (expr vars
282 &optional
283 (ring *ring-of-integers*)
[1048]284 (order #'lex>)
[1170]285 (list-marker :[)
[1047]286 &aux
287 (ring-and-order (make-ring-and-order :ring ring :order order)))
[1168]288 "Evaluate Lisp form EXPR to a polynomial or a list of polynomials in
[1208]289variables VARS. Return the resulting polynomial or list of
290polynomials. Standard arithmetical operators in form EXPR are
291replaced with their analogues in the ring of polynomials, and the
292resulting expression is evaluated, resulting in a polynomial or a list
[1209]293of polynomials in internal form. A similar operation in another computer
294algebra system could be called 'expand' or so."
[1050]295 (labels ((p-eval (arg) (poly-eval arg vars ring order))
[1140]296 (p-eval-scalar (arg) (poly-eval-scalar arg))
[53]297 (p-eval-list (args) (mapcar #'p-eval args))
[989]298 (p-add (x y) (poly-add ring-and-order x y)))
[53]299 (cond
[1128]300 ((null expr) (error "Empty expression"))
[53]301 ((eql expr 0) (make-poly-zero))
302 ((member expr vars :test #'equalp)
303 (let ((pos (position expr vars :test #'equalp)))
304 (make-variable ring (length vars) pos)))
305 ((atom expr)
306 (coerce-coeff ring expr vars))
307 ((eq (car expr) list-marker)
308 (cons list-marker (p-eval-list (cdr expr))))
309 (t
310 (case (car expr)
311 (+ (reduce #'p-add (p-eval-list (cdr expr))))
312 (- (case (length expr)
313 (1 (make-poly-zero))
314 (2 (poly-uminus ring (p-eval (cadr expr))))
[989]315 (3 (poly-sub ring-and-order (p-eval (cadr expr)) (p-eval (caddr expr))))
316 (otherwise (poly-sub ring-and-order (p-eval (cadr expr))
[53]317 (reduce #'p-add (p-eval-list (cddr expr)))))))
318 (*
319 (if (endp (cddr expr)) ;unary
320 (p-eval (cdr expr))
[989]321 (reduce #'(lambda (p q) (poly-mul ring-and-order p q)) (p-eval-list (cdr expr)))))
[1106]322 (/
323 ;; A polynomial can be divided by a scalar
[1115]324 (cond
325 ((endp (cddr expr))
[1117]326 ;; A special case (/ ?), the inverse
[1119]327 (coerce-coeff ring (apply (ring-div ring) (cdr expr)) vars))
[1128]328 (t
[1115]329 (let ((num (p-eval (cadr expr)))
[1142]330 (denom-inverse (apply (ring-div ring)
331 (cons (funcall (ring-unit ring))
332 (mapcar #'p-eval-scalar (cddr expr))))))
[1118]333 (scalar-times-poly ring denom-inverse num)))))
[53]334 (expt
335 (cond
336 ((member (cadr expr) vars :test #'equalp)
337 ;;Special handling of (expt var pow)
338 (let ((pos (position (cadr expr) vars :test #'equalp)))
339 (make-variable ring (length vars) pos (caddr expr))))
340 ((not (and (integerp (caddr expr)) (plusp (caddr expr))))
341 ;; Negative power means division in coefficient ring
342 ;; Non-integer power means non-polynomial coefficient
343 (coerce-coeff ring expr vars))
[989]344 (t (poly-expt ring-and-order (p-eval (cadr expr)) (caddr expr)))))
[53]345 (otherwise
346 (coerce-coeff ring expr vars)))))))
347
[1133]348(defun poly-eval-scalar (expr
349 &optional
350 (ring *ring-of-integers*)
351 &aux
352 (order #'lex>))
353 "Evaluate a scalar expression EXPR in ring RING."
354 (poly-lc (poly-eval expr nil ring order)))
355
[1189]356(defun spoly (ring-and-order f g
357 &aux
358 (ring (ro-ring ring-and-order)))
[55]359 "It yields the S-polynomial of polynomials F and G."
360 (declare (type poly f g))
361 (let* ((lcm (monom-lcm (poly-lm f) (poly-lm g)))
362 (mf (monom-div lcm (poly-lm f)))
363 (mg (monom-div lcm (poly-lm g))))
364 (declare (type monom mf mg))
365 (multiple-value-bind (c cf cg)
366 (funcall (ring-ezgcd ring) (poly-lc f) (poly-lc g))
367 (declare (ignore c))
368 (poly-sub
[1189]369 ring-and-order
[55]370 (scalar-times-poly ring cg (monom-times-poly mf f))
371 (scalar-times-poly ring cf (monom-times-poly mg g))))))
[53]372
373
[55]374(defun poly-primitive-part (ring p)
375 "Divide polynomial P with integer coefficients by gcd of its
376coefficients and return the result."
377 (declare (type poly p))
378 (if (poly-zerop p)
379 (values p 1)
380 (let ((c (poly-content ring p)))
[1203]381 (values (make-poly-from-termlist
382 (mapcar
383 #'(lambda (x)
384 (make-term (term-monom x)
385 (funcall (ring-div ring) (term-coeff x) c)))
386 (poly-termlist p))
387 (poly-sugar p))
388 c))))
[55]389
390(defun poly-content (ring p)
391 "Greatest common divisor of the coefficients of the polynomial P. Use the RING structure
392to compute the greatest common divisor."
393 (declare (type poly p))
394 (reduce (ring-gcd ring) (mapcar #'term-coeff (rest (poly-termlist p))) :initial-value (poly-lc p)))
[1066]395
[1091]396(defun read-infix-form (&key (stream t))
[1066]397 "Parser of infix expressions with integer/rational coefficients
398The parser will recognize two kinds of polynomial expressions:
399
400- polynomials in fully expanded forms with coefficients
401 written in front of symbolic expressions; constants can be optionally
402 enclosed in (); for example, the infix form
403 X^2-Y^2+(-4/3)*U^2*W^3-5
404 parses to
405 (+ (- (EXPT X 2) (EXPT Y 2)) (* (- (/ 4 3)) (EXPT U 2) (EXPT W 3)) (- 5))
406
407- lists of polynomials; for example
408 [X-Y, X^2+3*Z]
409 parses to
410 (:[ (- X Y) (+ (EXPT X 2) (* 3 Z)))
411 where the first symbol [ marks a list of polynomials.
412
413-other infix expressions, for example
414 [(X-Y)*(X+Y)/Z,(X+1)^2]
415parses to:
416 (:[ (/ (* (- X Y) (+ X Y)) Z) (EXPT (+ X 1) 2))
417Currently this function is implemented using M. Kantrowitz's INFIX package."
418 (read-from-string
419 (concatenate 'string
420 "#I("
421 (with-output-to-string (s)
422 (loop
423 (multiple-value-bind (line eof)
424 (read-line stream t)
425 (format s "~A" line)
426 (when eof (return)))))
427 ")")))
428
[1145]429(defun read-poly (vars &key
430 (stream t)
431 (ring *ring-of-integers*)
432 (order #'lex>))
[1067]433 "Reads an expression in prefix form from a stream STREAM.
[1144]434The expression read from the strem should represent a polynomial or a
435list of polynomials in variables VARS, over the ring RING. The
436polynomial or list of polynomials is returned, with terms in each
437polynomial ordered according to monomial order ORDER."
[1146]438 (poly-eval (read-infix-form :stream stream) vars ring order))
[1092]439
[1146]440(defun string->poly (str vars
[1164]441 &optional
[1146]442 (ring *ring-of-integers*)
443 (order #'lex>))
444 "Converts a string STR to a polynomial in variables VARS."
[1097]445 (with-input-from-string (s str)
[1165]446 (read-poly vars :stream s :ring ring :order order)))
[1095]447
[1143]448(defun poly->alist (p)
449 "Convert a polynomial P to an association list. Thus, the format of the
450returned value is ((MONOM[0] . COEFF[0]) (MONOM[1] . COEFF[1]) ...), where
451MONOM[I] is a list of exponents in the monomial and COEFF[I] is the
452corresponding coefficient in the ring."
[1171]453 (cond
454 ((poly-p p)
455 (mapcar #'term->cons (poly-termlist p)))
456 ((and (consp p) (eq (car p) :[))
[1172]457 (cons :[ (mapcar #'poly->alist (cdr p))))))
[1143]458
[1164]459(defun string->alist (str vars
460 &optional
461 (ring *ring-of-integers*)
462 (order #'lex>))
[1143]463 "Convert a string STR representing a polynomial or polynomial list to
[1158]464an association list (... (MONOM . COEFF) ...)."
[1166]465 (poly->alist (string->poly str vars ring order)))
[1440]466
467(defun poly-equal-no-sugar-p (p q)
468 "Compare polynomials for equality, ignoring sugar."
469 (equalp (poly-termlist p) (poly-termlist q)))
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