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D.2.11.2 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';
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