08-211
To: J3
From: Michael Ingrassia
Subject: Public Comment J32003
Date: 2008 June 17
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From burnus@net-b.de Mon Jun 16 11:21:51 2008
Date: 2008 June 17
Subject: F2008 comment to BESSEL_YN/BESSEL_JN
To: f2008-ballot-comments-ext@sun.com

Hello,

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.

Best regards,

Tobias Burnus,
using/programming electronic-structure Fortran 90+ codes and
co-developing the GNU Fortran compiler

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