Re: efficient vector/matrix operations in Ada

[dmitry@elros.cbb-automation.de (Dmitry Kazakov)]

On 10 Aug 2001 09:54:33 -0700, B_Gaffney@My-Deja.com (B.Gaffney)
wrote:

>"Russ P." <18k11tm001@sneakemail.com> wrote in message news:<3B6F5ABC.3C40E189@sneakemail.com>...
>> No, you really need the dynamically instantiated temporary matrix, I
>> believe. I've been through this little lesson years ago. Don't forget
>> that you also need to be able to handle expressions such as "A = B + C +
>> D;". You can play complicated games with static arrays of "work"
>> matrices, but you are asking for trouble and the resulting code is
>> likely to not be re-entrant.
>
>Um, OK, but how would you handle this case using your "+="
>implementation?  That was your original point wasn't it?

One could allow to define "accelerators" for binary and unary
operations. For instance:

   function "+" (A, B : Matrix) return Matrix;
   procedure InPlaceSum (A : in out Matrix, B : Matrix);
   pragma Accelerator (InPlaceSum, "+");

The compiler should replace calls to "+" with calls to InPlaceSum if
the left argument is temporal. So B+C+D has to be compiled into:

InPlaceSum ("+"(B,C),D)

[or silently ignore the pragma (:-))]

As for +=, it would be nice to extend the set of operators in Ada.
However it should be done in a consistent manner, i.e. for each
operator @ there should a @:= counterpart. Like "<=:=" for "<=". A bit
cumsy, isn't it? And what to do with "and" or "abs"? (:-))

Regards,
Dmitry Kazakov