source: branches/f4grobner/ngrobner.lisp

;;; -*-  Mode: Lisp -*- 
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;;;                                                                              
;;;  Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>          
;;;                                                                              
;;;  This program is free software; you can redistribute it and/or modify        
;;;  it under the terms of the GNU General Public License as published by        
;;;  the Free Software Foundation; either version 2 of the License, or           
;;;  (at your option) any later version.                                         
;;;                                                                              
;;;  This program is distributed in the hope that it will be useful,             
;;;  but WITHOUT ANY WARRANTY; without even the implied warranty of              
;;;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               
;;;  GNU General Public License for more details.                                
;;;                                                                              
;;;  You should have received a copy of the GNU General Public License           
;;;  along with this program; if not, write to the Free Software                 
;;;  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
;;;                                                                              
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(in-package :ngrobner)

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;;
;; Conversion from internal to infix form
;;
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(defun coerce-to-infix (poly-type object vars)
  "Write a polynomial, polynomial list, termlist term
in infix form, using variables VARS. Can be used to display 
an internal form polynomial more readably."
  (case poly-type
    (:termlist
     `(+ ,@(mapcar #'(lambda (term) (coerce-to-infix :term term vars)) object)))
    (:polynomial
     (coerce-to-infix :termlist (poly-termlist object) vars))
    (:poly-list
     `([ ,@(mapcar #'(lambda (p) (coerce-to-infix :polynomial p vars)) object)))
    (:term
     `(* ,(term-coeff object)
         ,@(mapcar #'(lambda (var power) `(expt ,var ,power))
                   vars (coerce (term-monom object) 'list))))
    (otherwise
     object)))