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From: desj@ccrwest.UUCP (David desJardins)
Newsgroups: comp.lang.fortran
Subject: Re: Fortran 77 Style Guide
Message-ID: <348@ccrwest.UUCP>
Date: 3 Aug 90 23:51:04 GMT
References: <26B89BE1.4349@ics.uci.edu> <59012@lanl.gov>
Organization: IDA Center for Communications Research
Lines: 32

In article <59012@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
>>     6) Initialize COMMON blocks only in BLOCK DATA subprograms.
>
>[...]  Anyway, _wherever_ you
>do it, you _should_ initialize _all_ common data.

   I find it hard to believe that you really mean this (especially as
you are writing from LANL).  On Crays at least, and probably on a lot
of other machines, initialized storage is included, byte for byte, in
the executable (a.out) file.  In fact, if any item in the common block
is initialized, the whole block is included.
   This makes it *extremely* undesirable to write code like

	INTEGER ARRAY(10**8)
	LOGICAL FLAG
	COMMON /FOO/ ARRAY, FLAG
	DATA FLAG/.FALSE./

much less to initialize the array itself.  (The above is a natural
thing to write if you want to initialize a table the first time it is
used, but not subsequently.)  Doing this causes you to discover
rapidly just how much (or how little) disk space is available to you
:-).

   For that matter, I disagree with the whole premise that arrays
should be initialized.  If the initialization is not necessary for the
functioning of the program, it seems likely to mislead the reader, who
will probably think that the initialized value has some particular
purpose.  And, as noted above, it is probably better to initialize
large arrays in code rather than with DATA statements anyway.

   -- David desJardins