Changeset 21

Timestamp:

2012-06-12T20:25:56-07:00 (13 years ago)

Author:

Marek Rychlik

Message:

Introduced a boundary case to colon-ideal, when f is nil.

File:

• trunk/grobner.lisp (modified) (1 diff)

trunk/grobner.lisp

@@ -1674 +1674 @@
 J the polynomial W*H belongs to I."
   (cond
-   ((endp g)
-    ;;Id(G) consists of 0 only so W*0=0 belongs to Id(F)
-    (if (every #'poly-zerop f)
-        (error "First ideal must be non-zero.")
-      (list (make-poly
-             (list (make-term
-                    (make-monom (monom-dimension (poly-lm (find-if-not #'poly-zerop f)))
-                                :initial-element 0)
-                    (funcall (ring-unit ring))))))))
-   ((endp (cdr g))
-    (colon-ideal-1 ring f (car g) top-reduction-only))
-   (t
-    (ideal-intersection ring
-                        (colon-ideal-1 ring f (car g) top-reduction-only)
-                        (colon-ideal ring f (rest g) top-reduction-only)
-                        top-reduction-only))))
+    ((endp f))
+    ((endp g)
+     ;;Id(G) consists of 0 only so W*0=0 belongs to Id(F)
+     (if (every #'poly-zerop f)
+         (error "First ideal must be non-zero.")
+         (list (make-poly
+                (list (make-term
+                       (make-monom (monom-dimension (poly-lm (find-if-not #'poly-zerop f)))
+                                   :initial-element 0)
+                       (funcall (ring-unit ring))))))))
+    ((endp (cdr g))
+     (colon-ideal-1 ring f (car g) top-reduction-only))
+    (t
+     (ideal-intersection ring
+                         (colon-ideal-1 ring f (car g) top-reduction-only)
+                         (colon-ideal ring f (rest g) top-reduction-only)
+                         top-reduction-only))))
 
 (defun colon-ideal-1 (ring f g &optional (top-reduction-only $poly_top_reduction_only))