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D.2.6.1 changechar

Procedure from library ring.lib (see ring_lib).

Usage:
changechar(newr,c[,r]); newr,c=strings, r=ring

Create:
create a new ring with name `newr` and make it the basering if r is an existing ring [default: r=basering].
The new ring differs from the old ring only in the characteristic. If, say, (newr,c) = ("R","0,A") and the ring r exists, the new basering will have name R, characteristic 0 and one parameter A.

Return:
No return value

Note:
Works for qrings if map from old_char to new_char is implemented This proc uses 'execute' or calls a procedure using 'execute'. If you use it in your own proc, let the local names of your proc start with @.

Example:
 
LIB "ring.lib";
ring r=0,(x,y,u,v),(dp(2),ds);
changechar("R","2,A"); R;"";
==> // basering is now R
==> //   characteristic : 2
==> //   1 parameter    : A 
==> //   minpoly        : 0
==> //   number of vars : 4
==> //        block   1 : ordering dp
==> //                  : names    x y 
==> //        block   2 : ordering ds
==> //                  : names    u v 
==> //        block   3 : ordering C
==> 
changechar("R1","32003",R); R1;
==> // basering is now R1
==> //   characteristic : 32003
==> //   number of vars : 4
==> //        block   1 : ordering dp
==> //                  : names    x y 
==> //        block   2 : ordering ds
==> //                  : names    u v 
==> //        block   3 : ordering C
kill R,R1;
if(system("with","Namespaces")) {
if( nameof(Current) == "Ring" ) {
kill Top::R,Top::R1;
} else {
kill Ring::R,Ring::R1;
}
}


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