Changeset de222e in git

Timestamp:

Feb 16, 2012, 3:54:42 PM (11 years ago)

Author:

Martin Lee <martinlee84@…>

Branches:

(u'jengelh-datetime', 'ceac47cbc86fe4a15902392bdbb9bd2ae0ea02c6')(u'spielwiese', 'a800fe4b3e9d37a38c5a10cc0ae9dfa0c15a4ee6')

Children:

eb481bfd5b0d2091758933b4dc457ec82ff37ce7

Parents:

d9357b93f2957d0cd01e1c353822adb5598cc142

git-author:

Martin Lee <martinlee84@web.de>2012-02-16 15:54:42+01:00

git-committer:

Martin Lee <martinlee84@web.de>2012-04-04 14:42:25+02:00

Message:

chg: cheaper divisibility tests to discard wrong factors

File:

• factory/facFqBivar.cc (modified) (2 diffs)

factory/facFqBivar.cc

@@ -652 +652 @@
   adaptedLiftBound= 0;
   int d= degree (F), l= 0;
+  CanonicalForm buf0= mulNTL (buf (0,x), LCBuf, b);
+  CanonicalForm buf1= mulNTL (buf (1,x), LCBuf, b);
+  CanonicalForm test0, test1;
   for (CFListIterator i= factors; i.hasItem(); i++, l++)
   {
@@ -658 +661 @@
     else
     {
-      g= mulMod2 (i.getItem(), LCBuf, M);
-      g /= content (g, x);
-      if (fdivides (g, buf, quot))
-      {
-        reconstructedFactors.append (g);
-        factorsFoundIndex[l]= 1;
-        buf= quot;
-        d -= degree (g);
-        LCBuf= LC (buf, x);
-        T= Difference (T, CFList (i.getItem()));
-        F= buf;
-
-        // compute new possible degree pattern
-        bufDegs2= DegreePattern (T);
-        bufDegs1.intersect (bufDegs2);
-        bufDegs1.refine ();
-        if (bufDegs1.getLength() <= 1)
-        {
-          reconstructedFactors.append (buf);
-          break;
+      test1= mod (mulNTL (i.getItem() (1,x), LCBuf, b), M);
+      if (uniFdivides (test1, buf1))
+      {
+        test0= mod (mulNTL (i.getItem() (0,x), LCBuf, b), M);
+        if (uniFdivides (test0, buf0))
+        {
+          g= mulMod2 (i.getItem(), LCBuf, M);
+          if (b.getp() != 0)
+            g= b(g);
+          g /= content (g, x);
+          if (fdivides (g, buf, quot))
+          {
+            reconstructedFactors.append (g);
+            factorsFoundIndex[l]= 1;
+            buf= quot;
+            d -= degree (g);
+            LCBuf= LC (buf, x);
+            buf0= mulNTL (buf (0,x), LCBuf, b);
+            buf1= mulNTL (buf (1,x), LCBuf, b);
+            T= Difference (T, CFList (i.getItem()));
+            F= buf;
+
+            // compute new possible degree pattern
+            bufDegs2= DegreePattern (T);
+            bufDegs1.intersect (bufDegs2);
+            bufDegs1.refine ();
+            if (bufDegs1.getLength() <= 1)
+            {
+              reconstructedFactors.append (buf);
+              break;
+            }
+          }
         }
       }