A descent algorithm for - approximation of continuous functions with values in unitary space
A new approach is presented for constructing recurrence relations for the modified moments of a function with respect to the Gegenbauer polynomials.
The paper gives such an iterative method for special Chebyshev approxiamtions that its order of convergence is . Somewhat comparable results are found in [1] and [2], based on another idea.
We obtain, for entire functions of exponential type satisfying certain integrability conditions, a quadrature formula using the zeros of spherical Bessel functions as nodes. We deduce from this quadrature formula a result of Olivier and Rahman, which refines itself a formula of Boas.