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Manual Reference Pages  - bessel_jn (3fortran)

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BESSEL_JN(3) - [MATHEMATICS] Bessel function of the first kind

result = bessel_jn(n, x)

         elemental real(kind=KIND) function bessel_jn(n,x)

          integer(kind=**),intent(in) :: n
          real(kind=KIND),intent(in) :: x

        result = bessel_jn(n1, n2, x)

         real(kind=KIND) function bessel_jn(n1, n2, ,x)

         integer(kind=**),intent(in) :: n1
         integer(kind=**),intent(in) :: n2
         real(kind=KIND),intent(in) :: x

BESSEL_JN( N, X ) computes the Bessel function of the first kind of order N of X.

BESSEL_JN(N1, N2, X) returns an array with the Bessel function|Bessel functions of the first kind of the orders N1 to N2.

o	N : a non-negative scalar integer..
o	N1 : a non-negative scalar integer.
o	N2 : a non-negative scalar integer.
o	X : Shall be a scalar for BESSEL_JN(N,X) or an array For BESSEL_JN(N1, N2, X).

The result value of BESSEL_JN (N, X) is a processor-dependent approximation to the Bessel function of the first kind and order N of X.

The result of BESSEL_JN (N1, N2, X) is a rank-one array with extent MAX (N2-N1+1, 0). Element i of the result value of BESSEL_JN (N1, N2, X) is a processor-dependent approximation to the Bessel function of the first kind and order N1+i-1 of X.

Sample program:

    program demo_bessel_jn
    use, intrinsic :: iso_fortran_env, only : real_kinds, &
       & real32, real64, real128
    implicit none
    real(kind=real64) :: x = 1.0_real64
        x = bessel_jn(5,x)
        write(*,*)x
    end program demo_bessel_jn

Results:

          2.4975773021123450E-004

Fortran 2008

BESSEL_J0(3), BESSEL_J1(3), BESSEL_Y0(3), BESSEL_Y1(3), BESSEL_YN(3)

fortran-lang intrinsic descriptions