1 | ;;; -*- Mode: Lisp; Syntax: Common-Lisp; Package: Grobner; Base: 10 -*-
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2 | #|
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3 | *--------------------------------------------------------------------------*
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4 | | Copyright (C) 1994, Marek Rychlik (e-mail: rychlik@math.arizona.edu) |
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5 | | Department of Mathematics, University of Arizona, Tucson, AZ 85721 |
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6 | | |
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7 | | Everyone is permitted to copy, distribute and modify the code in this |
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8 | | directory, as long as this copyright note is preserved verbatim. |
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9 | *--------------------------------------------------------------------------*
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10 | |#
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11 | (defpackage "PRINTER"
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12 | (:export poly-print print-term print-monom)
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13 | (:use "COMMON-LISP"))
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14 |
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15 | (in-package "PRINTER")
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16 |
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17 | (proclaim '(optimize (speed 0) (space 0) (safety 3) (debug 3)))
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18 |
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19 | (defun poly-print (plist vars &optional (stream t))
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20 | "Prints a polynomial or a list of polynomials PLIST using infix syntax compatible
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21 | with most software systems. The following data representations are assumed:
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22 | 1) Polynomial list is ([ poly1 poly2 ...)
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23 | 2) Polynomial is a list (term1 term2 ...)
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24 | 3) Term is (monom . number)
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25 | 4) Monom is (number1 number2 ...) and is a list of powers at corresponding
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26 | variables
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27 | Variable names must be provided to the printer explicitly."
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28 | (cond
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29 | ((and (symbolp (car plist)) (string= (symbol-name (car plist)) "["))
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30 | (format stream "[ ")
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31 | (poly-print-2 (rest plist) vars stream)
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32 | (format stream " ]"))
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33 | ;; Not a list but a single polynomial
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34 | (t (poly-print-1 plist vars stream))))
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35 |
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36 | (defun poly-print-1 (p vars &optional (stream t))
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37 | "An auxillary function of POLY-PRINT. It prints a single polynomial P."
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38 | (labels ((infix-sum (l &optional (beg t))
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39 | (unless (endp l)
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40 | (infix-term (first l) beg)
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41 | (infix-sum (rest l) nil)))
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42 | (infix-term (l &optional beg)
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43 | (unless (zerop (cdr l))
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44 | (case (cdr l)
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45 | (1 (unless beg (format stream " + "))
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46 | (infix-monom (first l) vars t))
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47 | (-1 (format stream " - ") (infix-monom (first l) vars t))
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48 | (otherwise
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49 | (cond
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50 | ((plusp (cdr l)) (unless beg (format stream " + ")))
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51 | ((minusp (cdr l)) (format stream " - ")))
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52 | (format stream "~d" (abs (cdr l)))
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53 | (infix-monom (first l) vars nil)))))
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54 | (infix-monom (l vars &optional beg)
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55 | (cond
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56 | ((endp l) (when beg (format stream "~d" 1)))
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57 | (t
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58 | (unless (zerop (car l))
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59 | (unless beg (format stream " * "))
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60 | ;; if in x^n we have n=1 then print just x
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61 | (format stream "~a~:[^~d~;~*~]" (car vars)
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62 | (= (car l) 1) (car l)))
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63 | (infix-monom (rest l) (rest vars) (and (zerop (car l)) beg)))
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64 | )))
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65 | (if (endp p)
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66 | (format stream "0")
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67 | (infix-sum p)))
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68 | p)
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69 |
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70 | (defun poly-print-2 (plist vars stream &optional (beg t))
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71 | "An auxillary function of POLY-PRINT. It prints a comma-separated list of polynomials PLIST."
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72 | (unless (endp plist)
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73 | (unless beg (format stream ", "))
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74 | (poly-print-1 (first plist) vars stream)
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75 | (poly-print-2 (rest plist) vars stream nil)))
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76 |
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77 |
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78 | (defun print-term (l vars &optional (stream t) beg)
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79 | "An auxillary function of POLY-PRINT. It prints a single term L."
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80 | (unless (zerop (cdr l))
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81 | (case (cdr l)
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82 | (1 (unless beg (format stream " + "))
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83 | (print-monom (first l) vars stream t))
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84 | (-1 (format stream " - ") (print-monom (first l) vars stream t))
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85 | (otherwise
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86 | (cond
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87 | ((plusp (cdr l)) (unless beg (format stream " + ")))
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88 | ((minusp (cdr l)) (format stream " - ")))
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89 | (format stream "~d" (abs (cdr l)))
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90 | (print-monom (first l) vars stream nil)))))
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91 |
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92 | (defun print-monom (l vars &optional (stream t) beg)
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93 | "An auxillary function of POLY-PRINT. It prints a single monomial L."
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94 | (cond
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95 | ((endp l) (when beg (format stream "~d" 1)))
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96 | (t
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97 | (unless (zerop (car l))
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98 | (unless beg (format stream " * "))
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99 | ;; if in x^n we have n=1 then print just x
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100 | (format stream "~a~:[^~d~;~*~]" (car vars)
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101 | (= (car l) 1) (car l)))
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102 | (print-monom (rest l) (rest vars) stream (and (zerop (car l)) beg)))
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103 | ))
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