Matrix(R, A) : Rng, Mtrx -> Mtrx
Given a matrix A over a ring S having m rows and n columns,
and another ring R, return the m x n matrix over R obtained
by coercing the entries of A from S into R. The argument order
to ChangeRing(A, R) here is consistent with other forms of ChangeRing, while the Matrix(R, A) form of this function is
provided to be consistent with the matrix creation functions above, for
which the destination ring is the first argument, if supplied.
ChangeRing(A, f) : Mtrx, Map -> Mtrx
Given a matrix A over a ring S having m rows and n columns,
another ring R, and a map f:S -> R, return the
m x n matrix over R obtained
by applying f to each of the entries of A. The R may be omitted,
in which case it is taken to be the codomain of f.
Return whether the entries in the matrix A can be coerced into R
and the matrix resulting from ChangeRing(A, R) if so.
V2.28, 13 July 2023