“…It has been the subject of intensive investigation, in which conditions on functions are varied to obtain different estimates; see [8,20] and references therein. This inequality has been investigated, applied and generalized by many authors in different areas of mathematics, among others in inner product spaces [7], quadrature formulae [5,25], finite Fourier transforms [4], linear functionals [1,12], matrix traces [24], inner product modules over H * -algebras and C * -algebras [2,11],…”