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Subject: [boost] [decimal] Proposed portable implementation ofstd::decimal
From: Josh Quigley (0zeroth_at_[hidden])
Date: 2012-05-16 01:11:03


Hi all.

A first draft of this library is available at
https://sourceforge.net/projects/stddecimal/

Runs on MSVC10 and gcc 4.6.3.
Wraps the Intel implementation only,
Until we resolve the licencing issue, top-level README contains
detailed instructions about where to get 3rd party code and what to do
with it.

I'm keen on feedback on a particular point (although all feedback is
of course welcome!):

The current project can parse and execute the test cases maintained by
Mike Cowlishaw from http://speleotrove.com/decimal/ (referred to as
the Test Cases). To be completely clear, I also have normal, interface
testing test cases, I am *not* talking about those below.

 - Question: How useful do people feel the Test Cases to be?

I originally expected 99% of these tests to pass, but it turns out
that most of them require:
 - The operands to be parsed and stored at the precision they appear
in the Test Case file
 - The operation to be performed at precision of the operands
 - The high precision result to be rounded to the precision required
by the Test Cases.
 - The test inputs to be parsed with correct rounding in underflow
situations (not required by IEEE afaik)

The above requirements are based on my experience with the tests - it
is possible I'm making a blunder somewhere.

Since the Test Cases are really testing the 3rd party library, an
argument could be made they are not essential, or even desirable. I'm
inclined to think they would be very, very nice to have, as they would
give users a lot of confidence - I suspect user uptake would be poor
without this confidence.

So... what do people think?

Regards,
Josh.

(PS gmail seems to be confused about who 'boost' is, so apologies for
the cross-posts!)


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