Changeset 4869a17 in git for Singular/kutil.cc

Timestamp:

Sep 6, 1999, 5:43:33 PM (25 years ago)

Author:

Hans Schönemann <hannes@…>

Branches:

(u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')

Children:

b92f93c2773a0586ff73c90f27d97471c8be45e6

Parents:

b93963af1ae4b345400e16affffc6707a9e8143b

Message:

* hannes: fixed redtail-bug (bug_16)


git-svn-id: file:///usr/local/Singular/svn/trunk@3590 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• Singular/kutil.cc (modified) (2 diffs)

Singular/kutil.cc

@@ -2 +2 @@
 *  Computer Algebra System SINGULAR     *
 ****************************************/
-/* $Id: kutil.cc,v 1.33 1999-04-29 16:57:16 Singular Exp $ */
+/* $Id: kutil.cc,v 1.34 1999-09-06 15:43:33 Singular Exp $ */
 /*
 * ABSTRACT: kernel: utils for kStd
@@ -2325 +2325 @@
 poly redtail (poly p, int pos, kStrategy strat)
 {
-  poly h, hn;
-  int j, e, l;
-  int op;
-
-  if (strat->noTailReduction)
-  {
-    return p;
-  }
-  h = p;
-  hn = pNext(h);
-  while(hn != NULL)
-  {
-    op = pFDeg(hn);
-    e = pLDeg(hn,&l)-op;
-    j = 0;
-    while (j <= pos)
-    {
-      if (pDivisibleBy(strat->S[j], hn)
-      && ((e >= strat->ecartS[j])
-        || strat->kHEdgeFound
-        || ((Kstd1_deg>0)&&(op<=Kstd1_deg)))
-      )
-      {
-        spSpolyTail(strat->S[j], p, h, strat->kNoether, strat->spSpolyLoop);
-        hn = pNext(h);
-        if (hn == NULL)
-        {
-          return p;
-        }
-        op = pFDeg(hn);
-        e = pLDeg(hn,&l)-op;
-        j = 0;
-      }
-      else
-      {
-        j++;
-      }
-    }
-    h = hn;
-    hn = pNext(h);
+
+  if ((!strat->noTailReduction)
+  && (pNext(p)!=NULL))
+  {
+    int j, e, l;
+    poly h = p;
+    poly hn = pNext(h); // !=NULL
+    int op = pFDeg(hn);
+    BOOLEAN save_HE=strat->kHEdgeFound;
+    strat->kHEdgeFound |= ((Kstd1_deg>0) && (op<=Kstd1_deg));
+    loop
+    {
+      e = pLDeg(hn,&l)-op;
+      j = 0;
+      while (j <= pos)
+      {
+        if (pDivisibleBy(strat->S[j], hn)
+        && ((e >= strat->ecartS[j])
+          || strat->kHEdgeFound)
+        )
+        {
+          spSpolyTail(strat->S[j], p, h, strat->kNoether, strat->spSpolyLoop);
+          hn = pNext(h);
+          if (hn == NULL) goto all_done;
+          op = pFDeg(hn);
+          if ((Kstd1_deg>0)&&(op>Kstd1_deg)) goto all_done;
+          e = pLDeg(hn,&l)-op;
+          j = 0;
+        }
+        else
+        {
+          j++;
+        }
+      } /* while (j <= pos) */
+      h = hn; /* better for: pIter(h); */
+      hn = pNext(h);
+      if (hn==NULL) break;
+      op = pFDeg(hn);
+      if ((Kstd1_deg>0)&&(op>Kstd1_deg)) break;
+    }
+all_done:
+    strat->kHEdgeFound = save_HE;
   }
   return p;