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From: "Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org>
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Subject: Re: GNAT compiler switches and optimization
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Jeffrey Creem wrote:
> 
> Specifically, one of the biggest speedups posted (and suggested by one 
> person on the bugzilla list) changes the Ada program so it is no longer 
> a pointer to an unconstrained array but rather a pointer to a 
> constrained array where the constrained array type definition is 
> determined at run time based on the size of the command line parameter.
> 
> This may seem like the same thing but where I am asserting this falls 
> apart is if someone wanted to write code that operated on variable sized 
> arrays, this approach would probably not work (i.e. dynamic creation of 
> a fixed length array).

You should be able to get the best of both worlds:

N : constant Positive := Integer'Value (Argument (1) );

type Base_Matrix is array (Positive range <>, Positive range <>)
of Float;

subtype Real_Matrix is Base_Matrix (1 .. N, 1 .. N);

-- 
Jeff Carter
"I unclog my nose towards you."
Monty Python & the Holy Grail
11