orresponds to the composition of linear maps.If R is a normed ring, then the condition of row or column finiteness can be relaxed.  With the norm in place, absolutely convergent series can be used instead of finite sums.  For example, the matrices whose column sums are absolutely convergent sequences form a ring.  Analogously of course, the matrices whose row sums are absolutely convergent series also form a ring.  In that vein, infinite matrices can also be used to describe operators on Hilbert spaces, where convergence and continuity questions arise, which again results in certain constraints that have to be imposed. However, the explicit point of view of matrices tends to obfuscate the matter,[nb 3] and the abstract and more powerful tools of functional analysis can be used instead.ශූන්‍ය න්‍යාස[සංස්කරණය]An empty matrix is a matrix in which the number of rows or columns (or both) is zero.[55][56] Empty matrices help dealing with maps involving the zero vector space. For example