An algorithm for fast and accurate evaluation of band-limited functions at many scattered points on the unit 2-d sphere is developed. The algorithm is based on trigonometric representation of spherical harmonics in spherical coordinates and highly localized tensor-product trigonometric kernels (needlets). It is simple, fast, local, memory efficient, numerically stable and with guaranteed accuracy. Comparison of this algorithm with other existing algorithms in the literature is also presented.
Kamen G. Ivanov, Pencho Petrushev