[fitsbits] top or bottom

[Mark Calabretta]

On Thu 2000/05/04 09:06:45 +0100, Patrick Wallace wrote
in a message to: fitsbits at nrao.edu

>Perhaps I've misunderstood both Mark's original point and the Fortran 90
>feature being demonstrated by Stephen, but wasn't the solution present in
>earlier Fortrans, in the form of the "adjustable dimension" feature?  It
>was certainly there in Fortran IV (ANSI X3.9-1966).

There were two points,

   1) The array is part of a larger "data structure" which contains
      everything needed to define the coordinate system.  This is so that
      you can treat a coordinate system as one object and maintain several
      of them simultaneously.  You can't build an adjustable (or assumed
      size) array into such a structure.

   2) The "data structure" also contains the inverse of the CD matrix and
      since fortran 77 has no memeory allocation facility this space has
      to be reserved.

Also, I confined myself to ANSI X3.9-1978 (FORTRAN 77), which doesn't
admit DEC (or other) extensions.  Even so this would only have helped
marginally since you can't have adjustable arrays in a RECORD (DEC FORTRAN
data structure).

I'm not familiar with FORTRAN 90.  Perhaps someone can say whether it
allows adjustable arrays inside data structures.

Mark Calabretta
ATNF