|
|
D.4.26.3 sagbi
Procedure from library sagbi.lib (see sagbi_lib).
- Usage:
- sagbi(A[, tr, mt]); A ideal, tr, mt optional integers
- Return:
- ideal, a SAGBI basis for A
- Assume:
- basering is not a qring
- Purpose:
- Computes a SAGBI basis for the subalgebra given by the generators in A.
| | The optional argument tr=tailred determines whether tail reduction will be performed.
- If (tailred=0), no tail reduction is performed,
- If (tailred<>0), tail reduction is performed.
The other optional argument meth determines which method is
used for Groebner basis computations.
- If mt=0 (default), the procedure std is used.
- If mt=1, the procedure slimgb is used.
|
Example:
| | LIB "sagbi.lib";
ring r= 0,(x,y,z),dp;
ideal A=x2,y2,xy+y;
//Default call, no tail-reduction is done.
sagbi(A);
==> _[1]=x2
==> _[2]=y2
==> _[3]=xy+y
==> _[4]=xy2+1/2y2
//---------------------------------------------
//Call with tail-reduction and method specified.
sagbi(A,1,0);
==> _[1]=x2
==> _[2]=y2
==> _[3]=xy+y
==> _[4]=xy2
|
|
