Changeset dd8047 in git

Timestamp:

Apr 6, 2011, 12:51:16 PM (12 years ago)

Author:

Martin Lee <martinlee84@…>

Branches:

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

Children:

09cb44379e8060a8d2ac1b71d07ebab1fd9e46e6

Parents:

1b8e048f850c69dc6881f43dc67b980d46ee540b

Message:

fix in bivariate factorization


git-svn-id: file:///usr/local/Singular/svn/trunk@14095 2c84dea3-7e68-4137-9b89-c4e89433aadc

Location:

factory

Files:

• facFqBivar.cc (modified) (3 diffs)
• facFqBivarUtil.cc (modified) (1 diff)
• facFqBivarUtil.h (modified) (1 diff)

factory/facFqBivar.cc

@@ -946 +946 @@
   if (factorNums < (int) logarithm)
     factorNums= (int) logarithm;
+  int subCheck1= substituteCheck (A, x);
+  int subCheck2= substituteCheck (A, y);
   for (int i= 0; i < factorNums; i++)
   {
@@ -966 +968 @@
       if (!fail)
       {
+        int dummy= subCheck2;
+        subCheck2= subCheck1;
+        subCheck1= dummy;
         A= buf;
         swap2= true;
@@ -1026 +1031 @@
     if (i == 0)
     {
-      int subCheck= substituteCheck (bufUniFactors);
-
-      if (subCheck > 1)
-      {
-        CanonicalForm bufA= A;
-        subst (bufA, bufA, subCheck, x);
-        factors= biFactorize (bufA, info);
-        reverseSubst (factors, subCheck, x);
-        appendSwapDecompress (factors, contentAxFactors, contentAyFactors,
-                              swap, swap2, N);
-        normalize (factors);
-        return factors;
-      }
-
-      if (!derivXZero && !fail2)
-      {
-        subCheck= substituteCheck (bufUniFactors2);
-        if (subCheck > 1)
+      if (subCheck1 > 0)
+      {
+        int subCheck= substituteCheck (bufUniFactors);
+
+        if (subCheck > 1 && (subCheck1%subCheck == 0))
+        {
+          CanonicalForm bufA= A;
+          subst (bufA, bufA, subCheck, x);
+          factors= biFactorize (bufA, info);
+          reverseSubst (factors, subCheck, x);
+          appendSwapDecompress (factors, contentAxFactors, contentAyFactors,
+                                swap, swap2, N);
+          normalize (factors);
+          return factors;
+        }
+      }
+
+      if (!derivXZero && !fail2 && subCheck2 > 0)
+      {
+        int subCheck= substituteCheck (bufUniFactors2);
+
+        if (subCheck > 1 && (subCheck2%subCheck == 0))
         {
           CanonicalForm bufA= A;

factory/facFqBivarUtil.cc

@@ -389 +389 @@
 }
 
+int
+substituteCheck (const CanonicalForm& F, const Variable& x)
+{
+  if (F.inCoeffDomain())
+    return 0;
+  if (degree (F, x) < 0)
+    return 0;
+  CanonicalForm f= swapvar (F, F.mvar(), x);
+  int sizef= 0;
+  for (CFIterator i= f; i.hasTerms(); i++, sizef++)
+  {
+    if (i.exp() == 1)
+      return 0;
+  }
+  int * expf= new int [sizef];
+  int j= 0;
+  for (CFIterator i= f; i.hasTerms(); i++, j++)
+    expf [j]= i.exp();
+
+  int indf= sizef - 1;
+  if (expf[indf] == 0)
+    indf--;
+
+  int result= expf[indf];
+  for (int i= indf - 1; i >= 0; i--)
+  {
+    if (expf [i]%result != 0)
+    {
+      delete [] expf;
+      return 0;
+    }
+  }
+
+  delete [] expf;
+  return result;
+}
+
 static int
 substituteCheck (const CanonicalForm& F, const CanonicalForm& G)

factory/facFqBivarUtil.h

@@ -191 +191 @@
              );
 
+/// check if a substitution x^n->x is possible
+///
+/// @return an integer n > 1, if a substitution described as above is possible
+///         else n <= 1
+int
+substituteCheck (const CanonicalForm& F, ///<[in] a polynomial
+                 const Variable& x       ///<[in] some variable
+                );
+
 #endif
 /* FAC_FQ_BIVAR_UTIL_H */