J Bessel Function

This document is an entry from the DECUS Program Library, dated September 6, 1967.

It describes a FORTRAN program (DECUS No. 8-96) titled "J BESSEL FUNCTION", authored by J. A. Crawford of Communications Systems, Inc.

The program's purpose is to compute the J Bessel function for a given argument and order. Users are prompted to input:

• The desired order (N) of the Bessel function.
• The argument (X) for the function.
• The desired accuracy.

The program outputs the calculated Bessel function value and an error code (IER). The error codes indicate:

• IER=0: No error.
• IER=1: Order is negative.
• IER=2: Argument is negative or zero.
• IER=3: Required accuracy not obtained.
• IER=4: Range of N with respect to X is not correct.

A standard disclaimer notes that while tested, no warranty is expressed or implied regarding its accuracy or functioning.