Re: How to access an array using two different indexing schemes

["Robin" <robin51@dodo.com.au>]

"Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message 
news:ov93ij$njh$1@dont-email.me...
> On 11/24/2017 12:42 PM, Jerry wrote:
>> I want to access an array such as Real_Vector (built-in for Ada >= 2005) with two different 
>> indexing schemes. For example, I would access a Real_Vector indexed (0 .. 4) when thinking of it 
>> as a times series and the same data indexed (1 .. 5) when thinking of it as a vector. Another 
>> application would be a vector indexed (-128 .. 127) because it fits my problem domain, perhaps a 
>> spatial variable, but I need to index it as (0 .. 255) when thinking of doing a Fast Fourier 
>> Transform on it.
>
> I can't think of any situation when I'd need to access the same component of an array using 
> different indices,

It can arise in boundary value problems, where operations are carried out
on all elements of a matrix except the first and last rows, and first and
last columns.

In PL/I, such situations are handled using the iSUB facility. 



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