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D.2.8.2 changeord

Procedure from library ring.lib (see ring_lib).

Usage:
changeord(neword[,r]); newordstr=list, r=ring/qring

Return:
ring R, obtained from the ring r [default: r=basering], by changing order(r) to neword.
If, say, neword=list(list("wp",intvec(2,3)),list(list("dp",1:(n-2)))); and if the ring r exists and has n variables, the ring R will be equipped with the monomial ordering wp(2,3),dp.

Example:
 
LIB "ring.lib";
ring r=0,(x,y,u,v),(dp(2),ds);
def R=changeord(list(list("wp",intvec(2,3)),list("dp",1:2))); R; "";
==> //   characteristic : 0
==> //   number of vars : 4
==> //        block   1 : ordering wp
==> //                  : names    x y
==> //                  : weights  2 3
==> //        block   2 : ordering dp
==> //                  : names    u v
==> //        block   3 : ordering C
==> 
ideal i = x^2,y^2-u^3,v;
qring Q = std(i);
def Q'=changeord(list(list("lp",nvars(Q))),Q); setring Q'; Q';
==> //   characteristic : 0
==> //   number of vars : 4
==> //        block   1 : ordering lp
==> //                  : names    x y u v
==> //        block   2 : ordering C
==> // quotient ring from ideal
==> _[1]=v
==> _[2]=x2
==> _[3]=y2-u3
kill R,Q,Q';