besselj, a C code which evaluates Bessel J functions of noninteger order.


The computer code and data files made available on this web page are distributed under the MIT license


besselj is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:


fn, a C code which approximates elementary and special functions using Chebyshev polynomials; functions include Airy, Bessel I, J, K and Y, beta, confluent hypergeometric, error, gamma, log gamma, Pochhammer, Spence; integrals include hyperbolic cosine, cosine, Dawson, exponential, logarithmic, hyperbolic sine, sine; by Wayne Fullerton.

polpak, a C code which evaluates certain mathematical functions, especially some recursive polynomial families.

test_values, a C code which stores values of many mathematical functions, and can be used for testing.


  1. Donald Amos, SL Daniel, MK Weston,
    CDC 6600 subroutines IBESS and JBESS for Bessel functions I(NU,X) and J(NU,X),
    ACM Transactions on Mathematical Software,
    Volume 3, Number 1, March 1977, pages 76-92.
  2. William Cody,
    Algorithm 715: SPECFUN - A Portable FORTRAN Package of Special Function Routines and Test Drivers,
    ACM Transactions on Mathematical Software,
    Volume 19, Number 1, March 1993, pages 22-32.

Source Code:

Last revised on 08 June 2019.