Changeset 1063

Timestamp:

2015-06-10T09:08:15-07:00 (10 years ago)

Author:

Marek Rychlik

Message:

* empty log message *

File:

• branches/f4grobner/.junk/poly-eval.lisp (modified) (1 diff)

branches/f4grobner/.junk/poly-eval.lisp

@@ -163 +163 @@
 
 
+(defun parse-string-to-alist (str vars)
+  "Parse string STR and return a polynomial as a sorted association
+list of pairs (MONOM . COEFFICIENT). For example:
+(parse-string-to-alist \"[x^2-y^2+(-4/3)*u^2*w^3-5,y]\" '(x y u w))
+ ([ (((0 0 2 3) . -4/3) ((0 2 0 0) . -1) ((2 0 0 0) . 1)
+     ((0 0 0 0) . -5))
+    (((0 1 0 0) . 1)))
+The functions PARSE-TO-SORTED-ALIST and PARSE-STRING-TO-SORTED-ALIST
+sort terms by the predicate defined in the ORDER package."
+  (with-input-from-string (stream str)
+    (parse-to-alist vars stream)))
+
+
+(defun parse-to-sorted-alist (vars &optional (order #'lex>) (stream t))
+  "Parses streasm STREAM and returns a polynomial represented as 
+a sorted alist. For example:
+(WITH-INPUT-FROM-STRING (S \"X^2-Y^2+(-4/3)*U^2*W^3-5\")
+  (PARSE-TO-SORTED-ALIST '(X Y U W) S))
+returns
+(((2 0 0 0) . 1) ((0 2 0 0) . -1) ((0 0 2 3) . -4/3) ((0 0 0 0) . -5))
+and
+(WITH-INPUT-FROM-STRING (S \"X^2-Y^2+(-4/3)*U^2*W^3-5\")
+  (PARSE-TO-SORTED-ALIST '(X Y U W) T #'GRLEX>) S)
+returns
+(((0 0 2 3) . -4/3) ((2 0 0 0) . 1) ((0 2 0 0) . -1) ((0 0 0 0) . -5))"
+  (sort-poly (parse-to-alist vars stream) order))
+
+(defun parse-string-to-sorted-alist (str vars &optional (order #'lex>))
+  "Parse a string to a sorted alist form, the internal representation
+of polynomials used by our system."
+  (with-input-from-string (stream str)
+    (parse-to-sorted-alist vars order stream)))
+
+(defun sort-poly-1 (p order)
+  "Sort the terms of a single polynomial P using an admissible monomial order ORDER.
+Returns the sorted polynomial. Destructively modifies P."
+  (sort p order :key #'first))
+
+;; Sort a polynomial or polynomial list
+(defun sort-poly (poly-or-poly-list &optional (order #'lex>))
+  "Sort POLY-OR-POLY-LIST, which could be either a single polynomial
+or a list of polynomials in internal alist representation, using
+admissible monomial order ORDER. Each polynomial is sorted using
+SORT-POLY-1."
+  (cond
+   ((eql poly-or-poly-list :syntax-error) nil)
+   ((null poly-or-poly-list) nil)
+   ((eql (car poly-or-poly-list) '[)
+    (cons '[ (mapcar #'(lambda (p) (sort-poly-1 p order)) 
+                     (rest poly-or-poly-list))))
+   (t (sort-poly-1 poly-or-poly-list order))))
+