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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: matrix package with Ada
Newsgroups: comp.lang.ada
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Date: Tue, 20 Jul 2010 09:27:26 +0200
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On Mon, 19 Jul 2010 17:34:25 -0500, Randy Brukardt wrote:

> I am no expert on numerics, but I have to wonder what other languages and/or 
> packages do in such cases? Perhaps they just don't care (there is precedent 
> for that; Ada takes great pains to define the accuracy of most of the 
> numerical functions, most other languages say nothing at all). Clearly, this 
> problem would need to be solved in some way before a general routine could 
> in introduced (of course, the abstract above seems to imply that such a 
> solution is impossible).

"Accuracy requirements for the subprograms Solve, Inverse, Determinant,
Eigenvalues and Eigensystem are implementation defined."
      -- ARM G.3.1

I agree that it is not good from Ada design point of view. The requirement
should be: the accuracy is the precision of the corresponding Real type (or
else Constraint_Error).

This is an immense problem, especially for generic units, I have no idea
how to approach it using existing language means, not to mention
algorithmic issues.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de