Bessel functions - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Bessel functions (/thread-9404.html) Bessel functions - salvomic - 10-30-2017 10:21 PM hi everybody, there is a good post in the HP Prime Software part of the Forum (here) about the Bessel functions of 1st kind, by Eddie W. Shore and roadrunner. I need some help to implementate in a simple way also the 2nd kind functions, starting or not by the functions proposed by Eddie and roadrunner. Any help will be appreciated, thank you. Salvo RE: Bessel functions - toml_12953 - 10-31-2017 01:12 AM (10-30-2017 10:21 PM)salvomic Wrote:  hi everybody, there is a good post in the HP Prime Software part of the Forum (here) about the Bessel functions of 1st kind, by Eddie W. Shore and roadrunner. I need some help to implementate in a simple way also the 2nd kind functions, starting or not by the functions proposed by Eddie and roadrunner. Any help will be appreciated, thank you. Salvo Here's one I converted from a C program I found at Bessel Second Kind (the Prime comes up with a different answer. The answer in the code is right - I don't know why the Prime is so far off.): N.B. The code below changes LOG to LN which fixes the problem in the original code. Code: ```//************************************************************************ //*                                                                      * //*    Program to calculate the second kind Bessel function of integer   * //*    order N, for any REAL X, using the function BESSY(N,X).           * //*                                                                      * //* -------------------------------------------------------------------- * //*                                                                      * //*    SAMPLE RUN:                                                       * //*                                                                      * //*    (Calculate Bessel function for N:=2, X:=0.75).                    * //*                                                                      * //*    Second kind Bessel function of order  2 for X =  0.7500:          * //*                                                                      * //*         Y := -2.62974604                                             * //*                                                                      * //* -------------------------------------------------------------------- * //*   Reference: From Numath Library By Tuan Dang Trong in Fortran 77.   * //*                                                                      * //*                               C++ Release 1.0 By J-P Moreau, Paris.  * //*                                        (www.jpmoreau.fr)             * //*                                  Converted to HPPL by Tom Lake       * //***********************************************************************/ BESSJ0 (X) BEGIN //*********************************************************************** //      This subroutine calculates the First Kind Bessel Function of //      order 0, for any real number X. The polynomial approximation by //      series of Chebyshev polynomials is used for 0