Re: equivalence with dummy arguments

From: Ryo Furue (furufuru_at_ccsr.u-tokyo.ac.jp)
Date: 11/19/04 

Date: 19 Nov 2004 13:38:48 -0800

Richard E Maine <nospam@see.signature> wrote in message news:<m1wtwi4zi9.fsf@MLMCE0000L22801.local>...
> furufuru@ccsr.u-tokyo.ac.jp (Ryo Furue) writes:
>
> > Richard Maine <nospam@see.signature> wrote in message news:<87brdvoog2.fsf@vega.site>...

> I think I've said all that I can usefully do so on this. I've attempted
> to present my speculation about possible reasons. I'm already out on
> a limb. I simply have no basis at all to argue about whether there are
> other ways to also look at things. Of course, there are other ways;
> I would not dream of implying otherwise.

First of all, I have no intention whatsoever to argue against
what you are saying. You offered your speculation. There's
no point in arguing against it because other views are of
course posssible. (If you find my language impolite or harsh,
considered it as due to the fact that I'm not a native speaker
of English. I'm trying to be not agressive but clear.)

Rather, there is one point which is not clear to me in what
you are saying. I repeat I'm not arguing against your view,
or I'm not try to present a different one, but I'm trying
to understand yours.

In your first response, you said

> Note that *ALL* valid forms of equivalence are completely static
> and relate to do with compile-time layout of memory. [...]
> [...]
> What do you think that the main purpose of equivalence was?
>
> From what I see, [...] equivalence was mostly to save memory by
> using the same memory for different variables where practical.
> [...]
> Equivalence of dummy arguments wouldn't have much to do
> with compile-time memory layout to save memory.

What I'm trying to understand is this last sentence.
What does the saving of memory have to do with *compile-time*
memory layout? What's the logic?

I do understand that the saving of memory has to do with
memory layout. But why compile-time? I can't follow this
jump (which it seems to me to be) in logic.

In other words, there are two things: (1) All legal forms of
equivalence concern only about *compile-time* memory layout;
(2) Primary purpose of equivalence was to save memory.
I fail to see a logical connection between these two.

In short, what I do understand are:
(1') Equivalence concerns about memory layout;
(2) Primary purpose of equivalence was to save memory.
And what I don't understand is: How does the notion of
"compile-time" come into play in this picture?

Sorry for this repetitive presentation of my question.
I've cast it in different forms so that the chance of
its getting across will be higher (I hope). If this fails,
I'll give it up.

Regards,
Ryo

Relevant Pages

  • Re: equivalence with dummy arguments
    ... Rich Townsend wrote: ... >> saving of memory space by equivalence. ... dummy arguments in Fortran are passed by ...
    (comp.lang.fortran)
  • Re: equivalence statement
    ... No, really, EQUIVALENCE comes from an era when every byte of ... memory was precious, rather than every megabyte. ... the problem of having to use array A in one part of the program ... are far easier to cope with than back in that era. ...
    (comp.lang.fortran)
  • Re: equivalence with dummy arguments
    ... >> Equivalence with dummy arguments is illegal. ... :) Thanks for your speculation. ... > and relate to do with compile-time layout of memory. ... > with compile-time memory layout to save memory. ...
    (comp.lang.fortran)
  • Re: equivalence with dummy arguments
    ... (big snip of discussion of EQUIVALENCE and dummy variables) ... From the quote, yes, it seems to be memory savings. ... Dummy arguments don't compile time memory allocated to them. ... In both cases the same dummy array is reused, ...
    (comp.lang.fortran)
  • Re: equivalence with dummy arguments
    ... I'd use EQUIVALENCE to organize storage in ways ... some machines it would transfer in double words instead ... Half as many memory cycles can make a big difference. ...
    (comp.lang.fortran)