D.4.2.7 select1

Procedure from library elim.lib (see elim_lib).

Usage:

select1(id,n[,m]); id ideal/module, n, m integers

Return:

generators of id containing the variable n
[at least one of the variables up to m]

Note:

use ’select’ for selecting generators containing all the variables between n and m

Example:

LIB "elim.lib";
ring r=0,(x,y,t,s,z),(c,dp);
ideal i=x-y,y-z2,z-t3,s-x+y3;
ideal j=select1(i,1);
j;
→ j[1]=x-y
→ j[2]=y3-x+s
module m=i*(gen(1)+gen(2));
m;
→ m[1]=[x-y,x-y]
→ m[2]=[-z2+y,-z2+y]
→ m[3]=[-t3+z,-t3+z]
→ m[4]=[y3-x+s,y3-x+s]
select1(m,1,2);
→ _[1]=[x-y,x-y]
→ _[2]=[-z2+y,-z2+y]
→ _[3]=[y3-x+s,y3-x+s]

See also: nselect; select.