Required operations motion
Dear P1788 group,
I request a motion about required operations.
-Dima
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Motion "Required Operations".
Operations required in all flavors of the standard IEEE 1788-2015
are required also in the simplified standard P1788.1 .
Specifically, 4 operations missed in the initial draft are required in P1788.1:
- arithmetic operations
roundTiesToEven(x)
roundTiesToAway(x)
- cancellative addition and subtraction
cancelPlus(x,y)
cancelMinus(x,y) .
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Rationale.
This (together with better conformance of interval literals) permits
more formal relation between IEEE 1788-2015 and P1788.1 .
It makes P1788.1 become a flavor of IEEE 1788-2015
though text of P1788.1 doesn't need to mention flavors.
If P1788.1 satisfies requirements of IEEE 1788-2015 flavor without any exemptions
it starts a good tradition of adding new flavors to IEEE 1788-2015.
The specification of roundTiesToXXX(x) and specification cancellative operations
doesn't add too much text to the P1788.1 .
There are simple implementations of these functions.
A possible implementation of roundTiesToXXX(x) operations can be found here:
https://java.net/projects/jinterval/sources/svn/content/trunk/jinterval/p1788-launcher-java/src/main/resources/net/java/jinterval/p1788/integerFuns.c?rev=379 .
And Michel Hack wrote how to do it simpler:
http://grouper.ieee.org/groups/1788/email/msg08423.html .
There are subtleties in implementation of cancellative operations
when the answer is nearly a one-point interval (or nearly undefined).
See notes in subsection 12.12.5 of IEEE 1788-2015.
Nevertheless, Marco Nehmeier suggested a solution:
http://grouper.ieee.org/groups/1788/email/msg07858.html .
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