Let 𝒜 be the space of all
analytic sequences, those complex sequences α for which there is a positive number r
such that ∑αnrn converges. Those linear transformations from 𝒜 to 𝒜 which have
matrix representations are characterized in terms of various spaces and topologies
associated with 𝒜 An example is given of a linear transformation from 𝒜 to 𝒜 which
has no matrix representation.