1

{*real type*} Real
types provide approximations to the real numbers, with relative bounds
on errors for floating point types, and with absolute bounds for fixed
point types.

2

3

{*root_real*} A
type defined by a real_type_definition
is implicitly derived from *root_real*, an anonymous predefined
(specific) real type. [Hence, all real types, whether floating point
or fixed point, are in the derivation class rooted at *root_real*.]

3.a

3.a.1/1

{*8652/0099*}
__Note that this derivation does not imply any inheritance of subprograms.
Subprograms are inherited only for types derived by a derived_type_definition
(see 3.4), or a private_extension_declaration
(see 7.3, 7.3.1, and 12.5.1).__

4

[{*universal_real* [partial]}
{*real literals*} Real
literals are all of the type *universal_real*, the universal type (see
3.4.1) for the class rooted at *root_real*,
allowing their use with the operations of any real type. {*universal_fixed*
[partial]} Certain multiplying operators have a result
type of *universal_fixed* (see 4.5.5), the
universal type for the class of fixed point types, allowing the result of the
multiplication or division to be used where any specific fixed point type is
expected.]

5

{*elaboration (real_type_definition)*
[partial]} The elaboration of a real_type_definition
consists of the elaboration of the floating_point_definition
or the fixed_point_definition.

6

An implementation shall perform the run-time evaluation
of a use of a predefined operator of *root_real* with an accuracy
at least as great as that of any floating point type definable by a floating_point_definition.

6.a

6.b

7

[For the execution of a predefined operation
of a real type, the implementation need not raise Constraint_Error if the result
is outside the base range of the type, so long as the correct result is produced,
or the Machine_Overflows attribute of the type is false (see G.2).]

8

{*nonstandard real type*}
An implementation may provide *nonstandard real types*,
descendants of *root_real* that are declared outside of the specification
of package Standard, which need not have all the standard characteristics of
a type defined by a real_type_definition.
For example, a nonstandard real type might have an asymmetric or unsigned base
range, or its predefined operations might wrap around or ``saturate'' rather
than overflow (modular or saturating arithmetic), or it might not conform to
the accuracy model (see G.2). Any type descended from
a nonstandard real type is also nonstandard. An implementation may place arbitrary
restrictions on the use of such types; it is implementation defined whether
operators that are predefined for ``any real type'' are defined for a particular
nonstandard real type. [In any case, such types are not permitted as explicit_generic_actual_parameters
for formal scalar types -- see 12.5.2.]

8.a

NOTES

9

32 As stated, real literals are of
the anonymous predefined real type *universal_real*. Other real types have
no literals. However, the overload resolution rules (see 8.6)
allow expressions of the type *universal_real* whenever a real type is
expected.

9.a

The syntax rule for real_type_definition
is modified to use the new syntactic categories floating_point_definition
and fixed_point_definition, instead
of floating_point_constraint and
fixed_point_constraint, because
the semantics of a type definition are significantly different than the
semantics of a constraint.

9.b

All discussion of model numbers, safe ranges,
and machine numbers is moved to 3.5.7, 3.5.8,
and G.2. Values of a fixed point type are now described
as being multiples of the *small* of the fixed point type, and we have
no need for model numbers, safe ranges, etc. for fixed point types.