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D.5.8.5 is_is

Procedure from library sing.lib (see section sing_lib).

Usage:

is_is(id); id ideal or poly

Return:

intvec = sequence of dimensions of singular loci of ideals generated by id[1]..id[i], k = 1..size(id);
dim(0-ideal) = -1;
id defines an isolated singularity if last number is 0

Note:

printlevel >=0: display comments (default)

Example:

LIB "sing.lib";
int p      = printlevel;
printlevel = 1;
ring r     = 32003,(x,y,z),ds;
ideal i    = x2y,x4+y5+z6,yx2+xz2+zy7;
is_is(i);
→ // dim of singular locus = 0
→ // isolated singularity if last number is 0 in dim-sequence:
→ 2,1,0
poly f     = xy+yz;
is_is(f);
→ // dim of singular locus = 1
→ // isolated singularity if last number is 0 in dim-sequence:
→ 1
printlevel = p;

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            User manual for Singular version 2-0-4, October 2002, generated by texinfo.