Changeset 2585

Timestamp:

2015-06-20T00:18:54-07:00 (10 years ago)

Author:

Marek Rychlik

Message:

* empty log message *

File:

• branches/f4grobner/polynomial.lisp (modified) (2 diffs)

branches/f4grobner/polynomial.lisp

@@ -86 +86 @@
   self)
 
+;; Fast destructive addition of termlists
+(defun fast-add-to (p q)
+  (macrolet ((lt (x) `(cadr ,x))
+             (lc (x) `(r-coeff (cadr ,x))))
+    (do ((p p)
+         (q q))
+        ((or (endp (cdr p)) (endp (cdr q)))
+         p)
+      (multiple-value-bind 
+            (greater-p equal-p)
+          (lex> (lm q) (lm p))
+        (cond
+          (greater-p
+           (rotatef (cdr p) (cdr q)))
+          (equal-p
+           (let ((s (add-to (lc p) (lc q))))
+             (if (r-zerop s)
+                 (setf (cdr p) (cddr p))
+                 (setf (lc p) s
+                       q (cdr q)))))))
+      (setf p (cdr p)))))
+
 (defmethod add-to ((self poly) (other poly))
   "Adds to polynomial SELF another polynomial OTHER.
@@ -91 +113 @@
 The result is stored in SELF. This implementation does
 no consing, entirely reusing the sells of SELF and OTHER."
-  (macrolet ((lt (termlist) `(car ,termlist))
-             (lc (termlist) `(r-coeff (car ,termlist))))
     (with-slots ((termlist1 termlist))
         self