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D.4.25.3 sagbiNF

Procedure from library sagbi.lib (see sagbi_lib).

Usage:
sagbiNF(id,dom,k[,n]); id either poly or ideal,dom ideal, k and n positive intergers.

Return:
same as type of id; ideal or polynomial.
 
    The integer k determines what kind of s-reduction is performed:
    - if (k=0) no tail s-reduction is performed.
    - if (k=1) tail s-reduction is performed.
    Three Algorithm variants are used to perform subalgebra reduction.
    The positive integer n determines which variant should be used.
    n may take the values (0 or default),1 or 2.

Note:
computation of subalgebra normal forms may be performed in polynomial rings or quotients thereof

Example:
 
LIB "sagbi.lib";
ring r=0,(x,y),dp;
ideal I= x2-xy;
qring Q=std(I);
ideal dom =x2,x2y+y,x3y2;
poly p=x4+x2y+y;
sagbiNF(p,dom,0);
==> 0
sagbiNF(p,dom,1);// tail subalgebra reduction is performed
==> 0


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            User manual for Singular version 3-1-1, Feb 2010, generated by texi2html.