Happy New Year.
Please find agenda for call on Redmine at
https://redmine.ogf.org/dmsf_files/13382?download=
Regards
Steve Hanson
Architect, IBM Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh(a)uk.ibm.com
tel:+44-1962-815848
Agree. Tracker updated.
Regards
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh(a)uk.ibm.com
tel:+44-1962-815848
From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com>
To: Steve Hanson/UK/IBM@IBMGB
Date: 10/12/2014 21:12
Subject: Re: [DFDL-WG] Binary decimal virtual point - unparsing
behaviour
(a) is more conservative, so I tend to want to go with that.
We have rounding functions in our DFDL expression language.
We know we're already on a design point here where the application will
have to implement truncation/rounding logic after any arithmetic operation
that can mess with the number of fraction digits that will be expressed.
You'd like to think that would be only multiplication/division - but I'm
not sure. Much depends on what is happening with xs:decimal values in the
application, and also depends on what the representation of xs:decimal
values is, in the application that is manipulating them.
The simplest way to see the issue is imagine the application is taking
decimal numbers, converting them to float, operating on float, and then
storing the result back into a decimal value of the DFDL infoset.
Consider 1.10 decimal. If you convert to float and back, you might get
1.099609375. This looks like it has a lot more precision, but in fact it
is the closest decimal value to the binary float value closest to 1.1
(decimal).
An application has to implement base 10 rounding or truncation on the
fractional part in order to insure that the behavior makes sense.
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are
subject to the OGF Intellectual Property Policy
On Wed, Dec 10, 2014 at 2:21 PM, Steve Hanson <smh(a)uk.ibm.com> wrote:
Sorry, but I need a clarification on this.
Spec says ""When unparsing a binary number (packed decimal or
twos-complement) and excess precision is supplied in the Infoset no
rounding occurs. It is a processing error.""
Technically, precision is the number of digits, and trailing zeros are
significant even after a decimal point.
So is it a processing error if I supply an infoset decimal value of 123.
990 and a BDVP of 2? While this can be serialized to an integer, the
original decimal has excess precision.
Similarly for an infoset decimal value of 12300.0 and a BDVP of -2. This
can be serialized to an integer, but the original decimal has excess
precision.
What this amounts to is whether we give a processing error a) whenever the
infoset supplies excess precision, or b) only when the excess precision
results in a decimal that can't be converted into an integer.
Regards
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh(a)uk.ibm.com
tel:+44-1962-815848
From: Steve Hanson/UK/IBM
To: DFDL-WG <dfdl-wg(a)ogf.org>
Date: 09/12/2014 17:45
Subject: Re: Binary decimal virtual point - unparsing behaviour
DFDL WG agreed that this is a processing error.
http://redmine.ogf.org/issues/249
Regards
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh(a)uk.ibm.com
tel:+44-1962-815848
From: Steve Hanson/UK/IBM
To: DFDL-WG <dfdl-wg(a)ogf.org>
Date: 05/12/2014 11:05
Subject: Binary decimal virtual point - unparsing behaviour
I am not finding anywhere in the DFDL spec that says explicitly what
happens during unparsing when a decimal value is given to the unparser,
and its rep is binary, and the BDVP is not sufficient to remove the
decimal point from the value. This is surely a processing error, because
the spec states in section 13.7.1 "When unparsing a binary number (packed
decimal or twos-complement) and excess precision is supplied in the
Infoset no rounding occurs. It is a processing error."
Regards
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh(a)uk.ibm.com
tel:+44-1962-815848
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Unless stated otherwise above:
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741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
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741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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