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KL · Joined: 16 Nov 2009 Posts: 155

I should have better put my example as

LitusSaxonicum · Posted: Mon Jan 24, 2011 11:07 pm Post subject:

Davidb:

Do you really (need logical operators) if all you have is an arithmetic IF (e.g. as in IBM1130 Fortran), or do they simply make the code more readable?

I'm still using this line, programmed in 1969 (I think) on said machine:

JohnCampbell · Joined: 16 Feb 2006 Posts: 2625 Location: Sydney

Klaus,

You wrote "We do not increase the portability of free format Fortran 9x if such simple definitions stay unclear."
My observation is that portability and the Fortran 9x standard are a bit mixed up.
They refused to give guidance on the values of KIND for integer and real.
I always thought that the 9x standard tried to introduce portability in OPEN but reading the fine print, "RECL=" was not standardised.

I think the rule that you should not use spaces within tokens should be applied wherever possible, such as .ne. or variabe_names. That being said, I never use ENDDO or ENDIF. (Ian, what is END CRITICAL ??)

John

IanLambley · Joined: 17 Dec 2006 Posts: 514 Location: Sunderland

END CRITICAL - I'm glad you asked me that - It is something to do with multiple images, see below as long as you don't then ask about SYNCH ALL etc. They are part of Fortran 2008.
Regards
Ian

KL · Joined: 16 Nov 2009 Posts: 155

Thanks for the comments. May be that ">" is better readable than ".gt." but also this form must be standardised. With the remark about arithmetic IF I do not agree. For very good reasons this construct is on the list of obsolete features. But I do agree -as already said- to write all operators in discussion without any blanks.

To increase portability was -at least as I understood- one of the major goals for the Fortran 90 development. And I think that this goal has been reached to a certain extent. But it is never a mistake to further increase it.

Klaus

LitusSaxonicum · Posted: Tue Jan 25, 2011 7:58 pm Post subject:

Klaus,

It wasn't a statement of belief (about logical IF), it was a question. Actually, it WAS possible to do without logical operators in constructing IFs, but their meaning very quickly becomes obscure, and whether or not the construct is obsolete, the logical IF is easier to understand later (although anyone can write impenetrable code if they try).

Surely the point I made about compound operators (like >=) is that in free format in FTN95 they cannot have spaces in, and if you want code that is future proofed and compilable by multiple compilers, you should go that way. I agree that > looks better than .gt., but I'm not sure that >= or /= is better than the dotty version - I don't like either as a matter of aesthetics. I much preferred (decades ago) Algol-60 which had reserved words, including logical operators. But Algol-60 was about as portable as a Durian on a long distance flight!

davidb: You can't have != because the ! would indicate that an inline comment followed.

Eddie

davidb · Joined: 17 Jul 2009 Posts: 560 Location: UK

JohnCampbell · Joined: 16 Feb 2006 Posts: 2625 Location: Sydney

Shame on you davidb !!
Your analysis misses all the nostalga of 1130 fortran.
When I first started work, I refused to use the 1130 and so these logical expressions were mere fokelore to me.