The safe numbers of a fixed point subtype AI-00508/03 1
88-05-23 BI WJ
| !standard 03.05.09 (11) 88-05-23 AI-00508/03
!class binding interpretation 86-11-14
| !status approved by WG9/AJPO 88-02-05
| !status approved by Director, AJPO 88-02-05
| !status approved by WG9/Ada Board 87-12-07
!status approved by Ada Board 87-07-30
!status panel/committee-approved 87-03-16 (reviewed)
!status panel/committee-approved (6-0-0) 86-11-14 (pending editorial review)
!status work-item 86-08-08
!status received 84-03-13
!references 83-00750
!topic The safe numbers of a fixed point subtype
!summary 86-12-28
The safe numbers of a fixed point subtype are the safe numbers of its base
type.
!question 86-12-28
3.5.9(11) defines the safe numbers of a fixed point TYPE. Shouldn't there
also be a definition for the safe numbers of a fixed point SUBtype (as there
is for floating point subtypes; see 3.5.7(9)).
!recommendation 86-12-28
The safe numbers of a fixed point subtype are the safe numbers of its base
type.
!discussion 87-03-13
Since 3.5.7(9) defines the safe numbers of a floating point subtype, a
similar definition should have been given for fixed point subtypes. The
intended definition was that the safe numbers of a subtype be those of its
base type. Safe numbers are used (in the Standard) to specify the accuracy
of real numeric operations. 4.5.7(8) defines the accuracy of all real
numeric operations in terms of the safe numbers (since the model numbers of a
type are a subset of the safe numbers and the rules for computing with safe
numbers are the same as the rules for computing with model numbers). Since
all numeric operations are declared for types rather than subtypes, these
operations are performed using the safe numbers of the base type, and hence,
it was intended for the safe numbers of a real subtype to be the same as the
safe numbers of its base type.