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D.4.7.6 nselect
Procedure from library elim.lib (see elim_lib).
- Usage:
- nselect(id,v); id = ideal, module or matrix, v = intvec
- Return:
- generators (or columns) of id not containing the variables with index
an entry of v
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;
nselect(i,3);
==> _[1]=x-y
==> _[2]=-z2+y
==> _[3]=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]
nselect(m,3..4);
==> _[1]=[x-y,x-y]
==> _[2]=[-z2+y,-z2+y]
nselect(matrix(m),3..4);
==> _[1,1]=x-y
==> _[1,2]=-z2+y
==> _[2,1]=x-y
==> _[2,2]=-z2+y
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See also:
select;
select1.
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