DETERMINATION OF A JUMP BY FOURIER AND FOURIER-CHEBYSHEV SERIES

By observing the equivalence of assertions on determining the jump of a‎ ‎function by its differentiated or integrated Fourier series‎, ‎we generalize a‎ ‎previous result of Kvernadze‎, ‎Hagstrom and Shapiro to the whole class of‎ ‎functions of harmonic bounded variation‎. ‎This is achieved without the finiteness assumption on‎ ‎the number of discontinuities‎. ‎Two results on determination of jump‎ ‎discontinuities by means of the tails of integrated Fourier-Chebyshev series are also derived.