Implementation of the imtx<T> interface using arrays of arrays.
class mtx_ptrs<T> : public imtx_impl
The mtx_ptrs<T> template is an implementation of the imtx<T> interface, and acts as a container of two-dimensional arrays of type T.
The class implements a storage method which maintains an array of pointers to homogenous arrays of type T. It is thus efficient as a data holder for existing functions which expect an array of pointers (i.e. T**).