8.25 BESSEL_J1 — Bessel function of the first kind of order 1

Description:

BESSEL_J1(X) computes the Bessel function of the first kind of order 1 of X. This function is available under the name BESJ1 as a GNU extension.

Standard:

Fortran 2008

Class:

Elemental function

Syntax:

RESULT = BESSEL_J1(X)

Arguments:

X	The type shall be REAL, and it shall be scalar.

Return value:

The return value is of type REAL and it lies in the range - 0.5818... \leq Bessel (0,x) \leq 0.5818 . It has the same kind as X.

Example:

          program test_besj1
            real(8) :: x = 1.0_8
            x = bessel_j1(x)
          end program test_besj1

Specific names:

Name	Argument	Return type	Standard
DBESJ1(X)	REAL(8) X	REAL(8)	GNU extension