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From: "Nasser M. Abbasi" <nma@12000.org>
Newsgroups: comp.lang.ada
Subject: Re: on using array index, vectorized operation
Date: Sun, 27 Mar 2011 15:00:22 -0700
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Date: 2011-03-27T15:00:22-07:00
List-Id: <comp.lang.ada>

Thanks Pascal and Shark8;

Yes, Pascal solution is a big improvment.

Here is what I have now: (will use the attributes 'succ and 'pred
later, but for now, I just wanted to see the concept first)

Also, notice, I need to use integer, not natural, for the indices, since
those can become negative in general.

------------- example ----------
procedure foo is

type buffer_t is array(integer range<>) of float;

u : buffer_t(-1..10) := (others=>0.0);

subtype r        is integer range u'first+1 .. u'last-1;
subtype r_plus_1 is integer range r'first+1 .. r'last+1;

begin

    u(r) := u(r) -  u(r_plus_1);

end foo;
----------------------

The above is workable solution for me, at least I avoid the
loops.

Only problem now is that I need to figure the castings I need
to do to make the compile happy, Since now I get the error:


$ gnatmake foo.adb
gcc-4.4 -c foo.adb
foo.adb:10:14: there is no applicable operator "-" for type "buffer_t" defined at line 2
gnatmake: "foo.adb" compilation error
$

Will look at this now, how best to solve this? I understand
that it want me to define a "-" operator for buffer_t. I really do
not want to cast things, I need to find the best solution to this.

May be I need to define a function "-" for buffer_t ?

Ok, back to editing and trying things :)

But I am happy now that at least I can avoid explicit loops if needed.

--Nasser