Changeset 28ffaa in git

Timestamp:

Aug 22, 2001, 4:20:47 PM (22 years ago)

Author:

Hans Schönemann <hannes@…>

Branches:

(u'spielwiese', '91fdef05f09f54b8d58d92a472e9c4a43aa4656f')

Children:

b6249e47ee58f2e950b5e85af745e7f054b42516

Parents:

a90dc01e741c2f1ba1d72b616559669433395640

Message:

* hannes: added search for main var to factorize


git-svn-id: file:///usr/local/Singular/svn/trunk@5596 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• factory/cf_factor.cc (modified) (6 diffs)

factory/cf_factor.cc

@@ -1 +1 @@
 /* emacs edit mode for this file is -*- C++ -*- */
-/* $Id: cf_factor.cc,v 1.10 1998-03-12 10:27:41 schmidt Exp $ */
+/* $Id: cf_factor.cc,v 1.11 2001-08-22 14:20:47 Singular Exp $ */
 
 //{{{ docu
@@ -37 +37 @@
 }
 
+void find_exp(const CanonicalForm & f, int * exp_f)
+{
+  if ( ! f.inCoeffDomain() )
+  {
+    int e=f.level();
+    CFIterator i = f;
+    if (i.exp() > exp_f[e]) exp_f[e]=i.exp();
+    for (; i.hasTerms(); i++ )
+    {
+      find_exp(i.coeff(), exp_f);
+    }
+  }
+}
+
+int find_mvar(const CanonicalForm & f)
+{
+  int mv=f.level();
+  int *exp_f=new int[mv+1];
+  int i;
+  for(i=mv;i>0;i--) exp_f[i]=0;
+  find_exp(f,exp_f);
+  for(i=mv;i>0;i--)
+  {
+    if ((exp_f[i]>0) && (exp_f[i]<exp_f[mv]))
+    {
+      mv=i;
+    }
+  }
+  delete[] exp_f;
+  return mv;
+}
+
 CFFList factorize ( const CanonicalForm & f, bool issqrfree )
 {
     if ( f.inCoeffDomain() )
-        return CFFList( f );
+        return CFFList( f );
     if ( getCharacteristic() > 0 ) {
-        ASSERT( f.isUnivariate(), "multivariate factorization not implemented" );
-        if ( isOn( SW_BERLEKAMP ) )
-            return FpFactorizeUnivariateB( f, issqrfree );
-        else
-            return FpFactorizeUnivariateCZ( f, issqrfree, 0, Variable(), Variable() );
+        ASSERT( f.isUnivariate(), "multivariate factorization not implemented" );
+        if ( isOn( SW_BERLEKAMP ) )
+            return FpFactorizeUnivariateB( f, issqrfree );
+        else
+            return FpFactorizeUnivariateCZ( f, issqrfree, 0, Variable(), Variable() );
     }
     else {
+        int mv=f.level();
+        if (! f.isUnivariate() )
+        {
+          mv=find_mvar(f);
+          if (mv!=f.level())
+          {
+            swapvar(f,Variable(mv),f.mvar());
+          }
+        }
         CanonicalForm cd = bCommonDen( f );
         CanonicalForm fz = f * cd;
@@ -54 +95 @@
         bool on_rational = isOn(SW_RATIONAL);
         Off(SW_RATIONAL);
-        if ( f.isUnivariate() )
-            F = ZFactorizeUnivariate( fz, issqrfree );
-        else
-            F = ZFactorizeMultivariate( fz, issqrfree );
+        if ( f.isUnivariate() )
+            F = ZFactorizeUnivariate( fz, issqrfree );
+        else
+            F = ZFactorizeMultivariate( fz, issqrfree );
         if ( on_rational )
             On(SW_RATIONAL);
@@ -69 +110 @@
                 F.insert( CFFactor( 1/cd ) );
             }
+        }
+        if ((mv!=f.level()) && (! f.isUnivariate() ))
+        {
+          CFFListIterator J=F;
+          for ( ; J.hasItem(); J++)
+          {
+            swapvar(J.getItem().factor(),Variable(mv),f.mvar());
+          }
+          swapvar(f,Variable(mv),f.mvar());
         }
         return F;
@@ -88 +138 @@
 
     if ( getCharacteristic() == 0 )
-        result = sqrFreeZ( f );
+        result = sqrFreeZ( f );
     else
-        result = sqrFreeFp( f );
+        result = sqrFreeFp( f );
 
     return ( sort ? sortCFFList( result ) : result );
@@ -99 +149 @@
 //    ASSERT( f.isUnivariate(), "multivariate factorization not implemented" );
     if ( getCharacteristic() == 0 )
-        return isSqrFreeZ( f );
+        return isSqrFreeZ( f );
     else
-        return isSqrFreeFp( f );
+        return isSqrFreeFp( f );
 }