# Bessel functions J n (z) and Y n (z) of integer order and complex argument

## Description

Abstract This paper describes computer subroutines which were developed to compute Bessel functions of the first and second kind (J_n (z) and Y_n (z), respectively) for a complex argument z and a range of integer orders. A novel way of determ ining the starting point of backward recurrence is used, and the algorithm for Y_n (z) improves on previous algorithms in terms of accuracy and restrictions on the range of orders. Title of program: BESCJY Catalogue Id: ACPH_v1_0 Nature of problem Bessel functions arise in the mathematical solution of physical problems, formulated in cylindrical and spherical coordinate systems. The CBESJY subroutine computes Jn(z) and Yn(z) for complex argument z and a sequence of integer orders n from M to N, where N >= 1 and M <= 0. Versions of this program held in the CPC repository in Mendeley Data ACPH_v1_0; BESCJY; 10.1016/0010-4655(93)90153-4 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)