Changeset 92550d in git for Singular/LIB/primdec.lib

Timestamp:

May 20, 2014, 5:18:40 PM (10 years ago)

Author:

Hans Schoenemann <hannes@…>

Branches:

(u'spielwiese', 'e7cc1ebecb61be8b9ca6c18016352af89940b21a')

Children:

a770fe2fceb17640c0d38e02178754f465f6ef5b

Parents:

984ff3b24d0cfc0f0c40172a5ef29ced17fd6741

Message:

fix: handle empty char. series in primdec.lib

File:

• Singular/LIB/primdec.lib (modified) (3 diffs)

Singular/LIB/primdec.lib

@@ -4006 +4006 @@
   }
   // remaining case: re[n+1] is trivial
-  // either n is at least number of variables or 
+  // either n is at least number of variables or
   // resolution happens to be shorter
   ideal ann=Ann(transpose(re[n]));
@@ -4152 +4152 @@
   matrix m=char_series(PS);  // We compute an irreducible
                              // characteristic series
+  if ((nrows(m)==1)
+  && (ncols(m)==1)
+  && (m[1,1]==1)) // in case of an empty series: min_ass_prim_charsets1
+  {
+    return min_ass_prim_charsets1(PS);
+  }
   int i,j,k;
   list PSI;
@@ -4251 +4257 @@
   matrix m=char_series(PS);  // We compute an irreducible
                              // characteristic series
+                             // this series may be empty (1x1: 1)
   int i,j,k;
+  while ((nrows(m)==1)
+  && (ncols(m)==1)
+  && (m[1,1]==1)) // in case of an empty series: permute the variables
+  {
+    n=string(var(nvars(oldring)));
+    for(i=1;i<nvars(oldring);i++) { n=n+","+string(var(i)); }
+    kill r;
+    execute("ring r=("+charstr(oldring)+"),("+n+"),dp;");
+    ideal PS=imap(oldring,PS);
+    matrix m=char_series(PS);
+  }
   ideal I;
   list PSI;