Changeset 22ab34 in git

Timestamp:

Aug 19, 2005, 12:59:19 PM (19 years ago)

Author:

Wilfred Pohl <pohl@…>

Branches:

(u'spielwiese', '4a9821a93ffdc22a6696668bd4f6b8c9de3e6c5f')

Children:

d116ec8d2a0671141e480634f435e120ecfdb2c9

Parents:

a73dde79cb0d6ba682d8ae94d597e8079aaf0e69

Message:

optimal variable for ezgcd


git-svn-id: file:///usr/local/Singular/svn/trunk@8536 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• factory/fac_ezgcd.cc (modified) (5 diffs)

factory/fac_ezgcd.cc

@@ -1 +1 @@
 /* emacs edit mode for this file is -*- C++ -*- */
-/* $Id: fac_ezgcd.cc,v 1.19 2005-05-03 09:35:34 Singular Exp $ */
+/* $Id: fac_ezgcd.cc,v 1.20 2005-08-19 10:59:19 pohl Exp $ */
 
 #include <config.h>
@@ -17 +17 @@
 #include "ftmpl_functions.h"
 
+#define OPTIMALVAR 1
+
+#ifdef OPTIMALVAR
+static Variable getOptimalVar( const CanonicalForm & FF, const CanonicalForm & GG );
+#endif
 
 static void findeval( const CanonicalForm & F, const CanonicalForm & G, CanonicalForm & Fb, CanonicalForm & Gb, CanonicalForm & Db, REvaluation & b, int delta, int degF, int degG );
@@ -28 +33 @@
 static modpk enlargeBound ( const CanonicalForm & F, const CanonicalForm & Lb, const CanonicalForm & Db, const modpk & pk );
 
+#ifdef OPTIMALVAR
+CanonicalForm ezgcd( const CanonicalForm & FF, const CanonicalForm & GG )
+{
+  CanonicalForm F,G;
+  REvaluation b;
+  Variable Z=getOptimalVar(FF,GG);
+//Test:  return Z;
+  if(Z==Variable(1)){return ezgcd( FF, GG, b, false );}
+  F=swapvar(FF,Z,Variable(1));
+  G=swapvar(GG,Z,Variable(1));
+  return swapvar(ezgcd( F, G, b, false ),Z,Variable(1));
+}
+#else
 CanonicalForm
 ezgcd ( const CanonicalForm & FF, const CanonicalForm & GG )
@@ -34 +52 @@
     return ezgcd( FF, GG, b, false );
 }
+#endif
 
 static CanonicalForm
@@ -359 +378 @@
     return modpk( p, i );
 }
+
+#ifdef OPTIMALVAR
+static Variable getOptimalVar( const CanonicalForm & FF, const CanonicalForm & GG )
+{
+  int ii,tt,d,dd,s,so;
+  CanonicalForm F,G,Fbz,Gbz,Dbz;
+  Variable opt=Variable(1);
+  if((FF.level()<3)||(GG.level()<3)){return opt;}
+  REvaluation bz=REvaluation(2,tmax(FF.level(),GG.level()),IntRandom(50));
+  Fbz=bz(FF);
+  Gbz=bz(GG);
+  Dbz=gcd(Fbz,Gbz);
+  dd=degree(Dbz);
+  so=size(Dbz);
+  tt=FF.level();
+  if(GG.level()<tt){tt=GG.level();}
+  for(ii=2;ii<=tt;ii++)
+  {
+    F=swapvar(FF,Variable(ii),Variable(1));
+    G=swapvar(GG,Variable(ii),Variable(1));
+    Fbz=bz(F);
+    Gbz=bz(G);
+    Dbz=gcd(Fbz,Gbz);
+    d=degree(Dbz);
+    if(d==dd)
+    {
+      s=size(Dbz);
+      if(s>so){so=s;opt=Variable(ii);}
+    }
+    if(d>dd){dd=d;so=size(Dbz);opt=Variable(ii);}
+  }
+  return opt;
+}
+#endif