Boundedness of linear operators in the space l2
Charles M. Bowden · International Journal of Quantum Chemistry · 2009
A necessary and sufficient condition for an operator to be bounded in a Hilbert space or a finite dimensional subspace of a Hubert space is derived explicitly in terms of the matrix elements of the matrix representation of the opeator. An identical condition for boundedness is shown to apply for the case of bilinear functionals in the space.