08-211r2 To: J3 From: Dan Nagle Subject: Public Comment J32003 Date: 2008 August 11 Commenter from Tobias Burnus: Fortran 2008 adds the BESSEL_YN and BESSEL_JN intrinsic procedures. These are special in so far that they belong into two classes: Class. Case (i): BESSEL_JN (N,X) is an elemental function. Case (ii): BESSEL_JN (N1,N2,X) is a transformational function. Having a procedure of dual nature is confusing and conceptually inconsistent. Furthermore, it increases the implementation burden for the compiler vendor. Additionally, I do not not see the need for the transformational function; the same functionality can easily gained by using the elemental function. I therefore strongly prefer to make BESSEL_YN and BESSEL_JN only elemental functions. If a burning need is seen for a BESSEL_*N(N1,N2,X) function (which I do not see), one should add a new intrinsic with a different name. J3 Response: Bessel functions of order greater than 1 are usually computed via recursion relations. Therefore, there is an efficiency gain by providing the transformational form.