(j3.2006) reverse section contiguous?

[Bill Long]

On 1/9/12 6:35 PM, Malcolm Cohen wrote:
>> "An object is contiguous if it is ...
>>
>>     (6) a nonzero-sized array section (6.5.3) provided that ...
>>
>>        (c) the elements of the section, in array element order, are a subset of
>>        the base object elements that are consecutive in array element order,"
>>
>> The elements of the section are  {A(10), A(9), A(8), ..., A(1)}  which, as a
>> set of elements, is a subset of {A(1), A(2), ..., A(10)}. (Perhaps "subset" is
>> a flawed word here.)
>
> This reading is ignoring the first "in array element order".  You should not
> just ignore the words of the standard like that!
>
> I agree that the wording could be better, but there is no plausible reading of
> this other than as a requirement on the ordering, and one that is not satisfied
> by the "backwards" sequence.  Seeing as how the discontiguous definition (which
> does not need to use the word "subset") also gives the "right" answer - i.e. the
> backwards section is definitively not contiguous - I see no need for an interp.
>
> In particular, an interp that did not change any wording would be a complete
> waste of time and energy.
>
> Let's just improve the wording in the next revision.  Preferably without using

That would be fine with me.

Cheers,
Bill


> "subsequence" (if someone can miscomprehend the existing ordering requirement
> even given the discontiguous definition, they can miscomprehend "subsequence"
> even more).  Splitting the ordering and subsetting requirements into two list
> items is more verbose but probably the best thing to do.
>
> Cheers,

-- 
Bill Long                                           longb at cray.com
Fortran Technical Support    &                 voice: 651-605-9024
Bioinformatics Software Development            fax:   651-605-9142
Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN 55101