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From: miner@ulowell.UUCP (Richard Miner)
Newsgroups: net.lang.f77
Subject: Re: f77 bug:  comparing logicals
Message-ID: <303@ulowell.UUCP>
Date: Sat, 3-May-86 20:48:47 EDT
Article-I.D.: ulowell.303
Posted: Sat May  3 20:48:47 1986
Date-Received: Tue, 6-May-86 06:03:53 EDT
References: <464@cubsvax.UUCP>
Reply-To: miner@ulowell.UUCP (Richard Miner)
Organization: University of Lowell
Lines: 35

In article <464@cubsvax.UUCP> peters@cubsvax.UUCP (Peter S. Shenkin) writes:
>The following program, compiled with f77, prints "f" for all three
>comparisons;  under VMS, using dec fortran,  the three results are
>"T", "F" and "T", as one would expect.
>
>cccccccccccccccccccccccc BEGIN HERE ccccccccccccccccccccccccccccccccccccccc
>	write(6,*)'.true. .eq. .true. :', .true. .eq. .true.
>	write(6,*)'.true. .eq. .false. :', .true. .eq. .false.
>	write(6,*)'.false. .eq. .false. :', .false. .eq. .false.
>
>	stop
>	end
>cccccccccccccccccccccccc END HERE cccccccccccccccccccccccccccccccccccccccccc

  The error is not that you get F F F as a result, the error is that the
compiler does not complain. .eq. and .ne. are not valid when used
with logical variables. They are for checking equalities with numeric
variabled not for checking equivalance. You should use .eqv. and .neqv.
for checking equivalence of logical variables and values.
  I found this out when porting our 36,000 line Graphical Kernel System -GKS
to the apollo. The F77 compiler on the system is not forgiving at all! The
biggest problem is the Brain damaged Fortran compiler under VMS. It lets 
you get away with too much non-standard code, even if you compile /standard.
  I will never recomend using VMS with FORTRAN as a development environment,
poor tools and as far as I am conserned a nasty compiler. I was talking to
a DEC Rep and he said that many people (at DEC) feel you should not port to
other environments, what an attitude!
  Most people have been asking for the GKS in C under Unix anyway. While
I am on the subject, we are writing our own Fortran -> C translator, does
anyone know of an existing one, in the PD preferably.
UUCP: !wanginst!ulowell!miner    Rich Miner
ARPA: miner@ulowell.CSNET        University of Lowell, Comp Sci Dept
TALK: (617) 452-5000 x2693       Lowell MA 01854 USA
HAL hears the 9000 series is not selling. "Please explain Dave. Why 
aren't HAL's selling?"  Bowman hesitates. "You aren't Amiga compatible."