I just began learning Julia and especially the package AbstractAlgebra.jl.
I succeeded in creating rings of polynomials: n=15 (for example, but I would like to do it for different ns)
T, x = PolynomialRing(ZZ, n, "x")
S, y = PolynomialRing(T, n , "y")
Now I would like to define a matrix with entries x[i]*y[j], for example with
M = [[x[i]*y[j] for i=1:n] for j=1:8]
but I realized this defines an array of arrays and NOT a matrix, so that I cannot compute its determinant, via
det(M)
How can I successfully define my polynomial matrix so that det(M) is a well defined polynomial in my ring S?