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Manuscript Title: A code to calculate (high order) Bessel functions based on the continued fractions method.
Authors: Yu.L. Ratis, P. Fernandez de Cordoba
Program title: BESSEL, SPHERICAL
Catalogue identifier: ACNL_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 76(1993)381
Programming language: Fortran.
Computer: VAX 6410.
Operating system: VAX/VMS.
Keywords: General purpose, High order, Bessel functions, Continued fractions, Method.
Classification: 4.7.

Nature of problem:
We include two codes in order to evaluate:
a) Bessel functions of fractional order (Subroutine SPHERICAL)
b) Bessel functions of integer order (Subroutine BESSEL)

Solution method:
We have developed a fast code to calculate Bessel functions of integer and fractional order based on the Continued Fractions method. This algorithm is specially useful in the case of Bessel functions of high order because it does not require any recalculation using normalization relations.

Restrictions:
We can use our algorithm for different order Bessel functions taking into account that the maximum order Nmax that we can reach with our method, for a fixed real positive value of z, is provided by the maximum real number defined in our machine: Nmax will be the maximum n for which Yn(z) is less than the maximum real number of our machine. (See text (LONG WRITE-UP: section 4))

Running time:
See text (LONG WRITE-UP: section 3).