Singular

If the basering is complex or real you can not
define another parameter and set minpoly.

What you can do, is to add a fourth variable, say a and
add the defining equation of the 5th root of unity as
polynomial in a as another generator to the ideals
which you declare for your computations.

Then the std-computations will reduce modulo this "minpoly"
and the results can be interpreted accordingly.

I apologize in advance if the answer to this question is obvious. It's entirely possible that I can't see the forest through the trees.

I'm making a complex ring.
ring r = (complex,30,i),(x,y,z),dp;
And I would like to work with the nth root of unity. For the sake of simplicity, let's look at the 5th root of unity.

What I want to do is add another parameter Q to the ring declaration and then
minpoly = rootofUnity(5);
or something like that.

But I can't figure out how to add another parameter to the complex ring.

Likely, the right way to do this is something completely different, but I'm spinning my wheels and not getting anywhere.

Thanks in advance for any assistance you can provide.
C.