Prereq.:either MATH 2057 and MATH 2090 or MATH 2057, MATH 2065 or MATH 2070 and MATH 2085. Sturm-Liouville problems, orthogonal functions (Bessel, Laguerre, Legendre, Hermite), orthogonal expansions including Fourier series, recurrence relations and generating functions, gamma and beta functions, Chebychev polynomials and other topics.