Singular

Hello,
I have calculated a list of (constant) matrices in one ring and now want to calculate their characteristic polynomials for which I need to define another ring but the list is not available in this new ring. How do I access the list in the new ring?
The documentation for the map function does not say how to transfer a list from one ring to another...


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One more elementary question: How do I do arithmetic on rational functions in Singular? For example calculate that

To map list from R to S, define a map, for example:
map phi=R,0;
and use phi(L) instead of L in S:
print(charpoly(phi(L)[i],"t");

For rational funktions: in a ring
ring R=(0,t),x,dp;
are the objects of type number rational functions, see (transcedental extension):
http://www.singular.uni-kl.de/Manual/3-1-0/sing_29.html

The ring map suggested does not work. Here is the suggested code:



And here is the error:



The suggestion about using a trancendental extension for working with rational functions was just what I wanted - Thanks!
Any ideas about the problem with the ring map above?

The problem is that there are no (canonical) mappings from
the coefficient field of R (Q(a)) to the the coeff. field of S (Q).
It should work with the following definition of S as a ring over Q(a):
ring S=(0,a),t,dp;

Ok, that worked. Of course, I had to define "minpoly" again for the ring S.

Thank you very much. But I have not noticed this use of "map":


in the documentation or in the Decker-Lossen book...(?)
Thanks again