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C Library Functions  - besj0 (3)

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NAME

besj0(3f) - [M_bessel] calculates the Bessel function J(X) of order zero.

CONTENTS

Synopsis
Description
Options
Authors
Example

SYNOPSIS

function besj0(xx)

DESCRIPTION

Series evaluation is used for small arguments, recurrence techniques are used for midrange, and Hankel-S Asymptotic Expansion is used for large arguments. Accuracy is between thirteen and fourteen correct significant figures except for large arguments where the accuracy eventually falls to eight figures.

OPTIONS

XX may be any doubleprecision argument.

AUTHORS

Originally from

   Sandia Mathematical Program Library
   Applied Mathematics Division 2642
   Sandia Laboratories
   P. O. box 5800
   Albuquerque, new Mexico  87115
   Control Data 6600 Version 5.1, 10 December 1973

       Written by    Ronald D. Halbgewachs, October 1,1971.

    IMPLEMENTATION

minor changes have been made to improve the portability or to confirm to modern Fortran standards

EXAMPLE

Sample program:

   program demo_besj0
   use, intrinsic :: iso_fortran_env, only : real32, real64, real128
   use, intrinsic :: iso_fortran_env, only : wp=>real64
   use M_bessel, only: besj0
   implicit none
   real(kind=wp)           :: y, z
   real(kind=wp),parameter :: x(*)=[-huge(0.0_wp),0.0_wp,-100.0_wp, &
   & 30000.0_wp,huge(0.0_wp)]
   integer                 :: i
      do i=1,size(x)
         y = bessel_j0(x(i))
         z = besj0(x(i))
         write(*,*)x(i),y,z
      enddo
   end program demo_besj0

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Nemo Release 3.1

besj0 (3)

February 23, 2025

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