Changeset dc2e7d5 in git for Singular/LIB

Timestamp:

Dec 11, 2013, 1:30:04 PM (10 years ago)

Author:

Hans Schoenemann <hannes@…>

Branches:

(u'spielwiese', '2a584933abf2a2d3082034c7586d38bb6de1a30a')

Children:

f1babfbabc0fc2906b36df32051eaaf09673dc6f

Parents:

3bc27a35af1aa573f7b8b110c0fda5e484414166

git-author:

Hans Schoenemann <hannes@mathematik.uni-kl.de>2013-12-11 13:30:04+01:00

git-committer:

Hans Schoenemann <hannes@mathematik.uni-kl.de>2013-12-11 13:33:06+01:00

Message:

fix: genus (tr.259)

Conflicts:
	Tst/Short/bug_532_s.res.gz.uu

File:

• Singular/LIB/normal.lib (modified) (5 diffs)

Singular/LIB/normal.lib

@@ -2156 +2156 @@
 
 proc genus(ideal I,list #)
-"USAGE:   genus(i) or genus(i,1); I a 1-dimensional ideal
+"USAGE:   genus(I) or genus(I,<option>); I a 1-dimensional ideal
 RETURN:  an integer, the geometric genus p_g = p_a - delta of the projective
          curve defined by i, where p_a is the arithmetic genus.
@@ -2162 +2162 @@
          i.e. dim(R'/R), R' the normalization of the local ring R of the
          singularity. @*
-         genus(i,1) uses the normalization to compute delta. Usually genus(i,1)
-         is slower than genus(i) but sometimes not.
+         genus(I,"nor") uses the normalization to compute delta. Usually genus(I,"nor")
+         is slower than genus(I) but sometimes not. @*
+         genus(I,"pri") starts with a primary decompsition.
 EXAMPLE: example genus; shows an example
 "
@@ -2169 +2170 @@
    int w = printlevel-voice+2;  // w=printlevel (default: w=0)
 
+   int ono,rpr,ll;
+   if(size(#)>0)
+   {
+     if(typeof(#[1])=="string")
+     {
+        if(#[1]=="nor"){ono=1;}
+        if(#[1]=="pri"){rpr=1;}
+     }
+     else { ERROR("invalid option for genus");}
+   }
    def R0=basering;
-   if(char(basering)>0)
+   if((char(basering)>0)||(ono))
    {
      def R1=changeord(list(list("dp",1:nvars(basering))));
@@ -2198 +2209 @@
        J=std(J);
      }
-     int pa=1-hilbPoly(J)[1];
-     pa=pa-deltaP(J);
+
+     list LL=normal(J,"prim");
+     int pa,i;
+     for(i=1;i<=size(LL[1]);i++)
+     {
+        def T=LL[1][i];
+        setring T;
+        pa=pa-hilbPoly(std(norid))[1];
+        setring S;
+        kill T;
+     }
+     pa=pa+1;
      setring R0;
      return(pa);
+   }
+   if(!rpr)
+   {
+      list LZ=minAssGTZ(I);
+      if(size(LZ)>1)
+      {
+         int p_g;
+         for(ll=1;ll<=size(LZ);ll++)
+         {
+            p_g=p_g+genus(LZ[ll],"pri")-1;
+         }
+         return(p_g+1);
+      }
+      else
+      {
+         I=LZ[1];
+      }
    }
    I=std(I);
@@ -2432 +2470 @@
    map sigma=S,var(1),var(2),1;
    ideal I=sigma(F);
-
-   if(size(#)!=0)
-   {                              //uses the normalization to compute delta
-      list nor=normal(I,"withDelta");
-      delt=nor[size(nor)][2];
-      genus=genus-delt-deltainf;
-      setring R0;
-      return(genus);
-   }
 
    ideal I1=jacob(I);