`BESSEL_JN`

— Bessel function of the first kind*Description*:`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.`BESSEL_JN(N1, N2, X)`

returns an array with the Bessel functions of the first kind of the orders`N1`to`N2`.*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)`

*Arguments*:-
`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. *Return value*:- The return value is a scalar of type
`REAL`

. It has the same kind as`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)`

GNU extension `REAL(8) X`