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C Library Functions  - besj1 (3)

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NAME

besj1(3f) - [M_bessel] calculates the Bessel function J(X) of order one.

CONTENTS

Synopsis
Description
Options
Authors
Example

SYNOPSIS

function besj1(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

X may be any doubleprecision argument

AUTHORS

Origin

     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

Changes were made for portability and to conform to newer Fortran standards.

EXAMPLE

Sample program:

   program demo_besj1
   use, intrinsic :: iso_fortran_env, only : real32, real64, real128
   use M_bessel, only: besj1
   implicit none
   real(kind=real64) :: x = 1.0_real64
      write(*,*)’value:   ’,x
      write(*,*)’bessel_1:’,bessel_j1(x)
      write(*,*)’besj1:   ’,besj1(x)
   end program demo_besj1

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Nemo Release 3.1

besj1 (3)

February 23, 2025

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