## BESSEL_JN intrinsic function

### Standard: F77 F90 F95 F2003 F2008 F2018 Example program

### ＜Syntax＞

**Elemental Form**

BESSEL_JN ( N, X )

N : Integer, with non-negative value;

X : Real;

Result : Same type and kind as X.

**Transformational Form**

BESSEL_JN ( N1, N2, X )

N1 : Integer scalar, with non-negative value;

N2 : Integer scalar, with non-negative value;

X : Real scalar;

Result : Vector of size `MAX(N2-N1+1,0)`

with the same type and kind as X.

### ＜Semantics＞

For the elemental form, the value of the result is an approximation to the Bessel function of the 1^{st} kind, order N, at the point X.
Being **elemental**, the result has the same shape as X or N, whichever is an array, with the operation being applied elementwise.
If both X and N are arrays, they must have the same shape.

For the transformational form, the value of the result is an approximation to the
Bessel function of the 1^{st} kind, orders N1 to N2, at the point X.
If N2<N1, the result will be a zero-sized array.

### ＜Related＞

BESSEL_J0 intrinsic function, BESSEL_J1 intrinsic function, BESSEL_Y0 intrinsic function, BESSEL_Y1 intrinsic function, BESSEL_YN intrinsic function