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From: FC138001@ysub.ysu.edu (Phil Munro)
Newsgroups: comp.lang.fortran
Subject: How do compilers handle dimensions?
Message-ID: <90198.114258FC138001@ysub.ysu.edu>
Date: 17 Jul 90 15:42:58 GMT
Organization: Youngstown State University VM system (YSUB)
Lines: 19


  All of my Fortran has been with mainframes and for the past year or
so I am using the VS2 compiler.  Probably my questions are simple, but
perhaps they will be of interest to others also.

1. The normal dimension byte size on the mainframe machine (which I
presume is a 64-bit machine) is *4.  Does this size, and the resulting
size of numbers, have anything to do with the bit size of a machine?
For example, a PC would have 8, 16, or 32 for the bit size depending
upon whether it is an XT-type, AT-type, or 386-type machine, as I
understand it.  If I transport a program from a 64-bit mainframe, will
the numerical precision for REAL numbers, and the maximum size for
INTEGERS, be less?  Would it be necessary to change variables to
DOUBLE PRECISION, or something like that, to get the same precision?

2. Are the dimension statements REAL*8, etc., part of Fortran 77, 90
or whatever, or are they just a VS extension?

  Thanks for any discussion on these things.  --Phil