
4.12 matrixObjects of type matrix are matrices with polynomial entries. Like polynomials they can only be defined or accessed with respect to a basering. In order to compute with matrices having integer or rational entries, define a ring with characteristic 0 and at least one variable. A matrix can be multiplied by and added to a poly; in this case the polynomial is converted into a matrix of the right size with the polynomial on the diagonal.
If A is a matrix then the assignment
