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From: ags@s.cc.purdue.edu (Dave Seaman)
Newsgroups: comp.lang.fortran
Subject: Re: CDC FORTRAN trivia questions
Keywords: arithmetic if logical
Message-ID: <3624@s.cc.purdue.edu>
Date: 1 Nov 88 19:27:14 GMT
References: <1196@helios.ee.lbl.gov> <3616@s.cc.purdue.edu> <7691@boring.cwi.nl>
Reply-To: ags@s.cc.purdue.edu.UUCP (Dave Seaman)
Organization: Purdue University
Lines: 22

In article <7691@boring.cwi.nl> dik@cwi.nl (Dik T. Winter) writes:
>Beware, .FALSE. is +0;  truth values returned by expressions could have any
>arithmetic value with negative for .TRUE. and positive for .FALSE..
>So -0 is .TRUE. (yes, it is a 1-s complement machine).

I still have access to a CDC 6500.  Just a few minutes ago I ran the
following program:

	print 10, .true., .false.
     10 format(2(1x,o20))
	end

for which the output was:

 77777777777777777776 00000000000000000000

which shows that .true. is -1 and .false. is 0, just as I said.  The older
compilers (such as RUN) used a different convention, something like -0 for
.true. and +0 for .false.

-- 
Dave Seaman	  					
ags@j.cc.purdue.edu