Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 38 3 2012 09 15 The coefficients of differentiated expansions of double and triple Jacobi polynomials739 766 en Eid Doha Cairo University-Faculty of Science-Mathematics Department Waleed Mohammed Abd-Elhameed Cairo University-Faculty of Science-Mathematics Department Hany Ahmed Helwan University-Faculty of Science-Mathematics Department 2010 11 15 Jacobi polynomials spectral methods hypergeometric series, Poisson’s equation