Singular

LIB "dmodloc.lib";
ring r = 0,(x,y,z,a,b,c),dp;
intvec v = 4,5,6;
def R = vars2pars(v);
setring R;
R;
==> //   characteristic : 0
==> //   3 parameter    : a b c 
==> //   minpoly        : 0
==> //   number of vars : 3
==> //        block   1 : ordering dp
==> //                  : names    x y z
==> //        block   2 : ordering C
v = 1,2;
def RR = vars2pars(v);
setring RR;
RR;
==> //   characteristic : 0
==> //   5 parameter    : a b c x y 
==> //   minpoly        : 0
==> //   number of vars : 1
==> //        block   1 : ordering dp
==> //                  : names    z
==> //        block   2 : ordering C