Dear John,
a brief addendum to a previous post of yours:
On Feb 20, 10:22 pm, John Palmieri <[EMAIL PROTECTED]> wrote:
> By the way, is the following a bug?
>
> sage: singular.LIB('ncall.lib')
> sage: R=singular.ring(0,'(x1,x12,x2)','dp')
> sage: C=singular.matrix(3,3,'1,-1,-1, -1,1,-1, -1,-1,1')
> sage: C
>
> 1, -1,-1,
> -1,1, -1,
> -1,-1,1
> sage: R=singular.ring(0,'(x1,x12,x2)','dp')
> sage: C
> `sage1`
As William pointed out, this is not a bug.
When re-defining R, then i think the matrix C is in fact lost.
However, it may be worth mentioning that after defining the 'same'
ring under a new name, it is easy to produce a copy of C in the new
ring; let R and C be defined as above. Then:
sage: newR=singular.ring(0,'(x1,x12,x2)','dp')
sage: C
`sage1`
sage: newC=R.fetch(C)
sage: newC
1, -1,-1,
-1,1, -1,
-1,-1,1
sage: R.set_ring()
sage: C
1, -1,-1,
-1,1, -1,
-1,-1,1
sage: newC
`sage3`
You see, a matrix (or an ideal) is only accessible if its ring is
active. But as long as the ring is not overwritten, the matrix isn't
lost.
Singular offers two commands to ship data from one ring to another:
fetch and imap. See
http://www.singular.uni-kl.de/Manual/latest/sing_197.htm#SEC237
and
http://www.singular.uni-kl.de/Manual/latest/sing_215.htm#SEC255
Cheers
Simon
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