BESSEL_JN — Bessel function of the first kind

BESSEL_JN(N, X)

BESSEL_JN(N, X) computes the Bessel function of the first kind of order N of X. This function is available under the name BESJN as a GNU extension. If N and X are arrays, their ranks and shapes shall conform.

Parameters

  • N – Shall be a scalar or an array of type INTEGER.

  • N1 – Shall be a non-negative scalar of type INTEGER.

  • N2 – Shall be a non-negative scalar of type INTEGER.

  • X – Shall be a scalar or an array of type REAL ; for BESSEL_JN(N1, N2, X) it shall be scalar.

Returns

The return value is a scalar of type REAL. It has the same kind as X.

Standard:

Fortran 2008 and later, negative N is allowed as GNU extension

Class:

Elemental function, except for the transformational function BESSEL_JN(N1, N2, X)

Syntax:

RESULT = BESSEL_JN(N, X)
RESULT = BESSEL_JN(N1, N2, X)
Note:

The transformational function uses a recurrence algorithm which might, for some values of X, lead to different results than calls to the elemental function.

Example:

program test_besjn
  real(8) :: x = 1.0_8
  x = bessel_jn(5,x)
end program test_besjn
Specific names:

Name

Argument

Return type

Standard

DBESJN(N, X)

INTEGER N REAL(8) X

REAL(8)

GNU extension