Contents Index Search Previous Next

1

{*highest
precedence operator*} {*operator
(highest precedence)*} {*abs
operator*} {*operator
(abs)*} {*absolute value*}
The highest precedence unary operator **abs**
(absolute value) is predefined for every specific numeric type *T*,
with the following specification:

2

3

{*not
operator*} {*operator
(not)*} {*logical operator:
See also not operator*} The highest precedence
unary operator **not** (logical negation) is predefined for every
boolean type *T*, every modular type *T*, and for every one-dimensional
array type *T* whose components are of a boolean type, with the
following specification:

4

5

The result of the operator **not** for a modular
type is defined as the difference between the high bound of the base
range of the type and the value of the operand. [For a binary modulus,
this corresponds to a bit-wise complement of the binary representation
of the value of the operand.]

6

The operator **not** that applies to a one-dimensional
array of boolean components yields a one-dimensional boolean array with
the same bounds; each component of the result is obtained by logical
negation of the corresponding component of the operand (that is, the
component that has the same index value). {*Range_Check*
[partial]} {*check, language-defined
(Range_Check)*} {*Constraint_Error
(raised by failure of run-time check)*} A
check is made that each component of the result belongs to the component
subtype; the exception Constraint_Error is raised if this check fails.

6.a

7

{*exponentiation
operator*} {*operator
(exponentiation)*} {***
operator*} {*operator
(**)*} The highest precedence *exponentiation*
operator ** is predefined for every specific integer type *T* with
the following specification:

8

9

Exponentiation is
also predefined for every specific floating point type as well as *root_real*,
with the following specification (where *T* is *root_real*
or the floating point type):

10

11

{*exponent*} The
right operand of an exponentiation is the *exponent*. The expression
X**N with the value of the exponent N positive is equivalent to the expression
X*X*...X (with N-1 multiplications) except that the multiplications are
associated in an arbitrary order. With N equal to zero, the result is
one. With the value of N negative [(only defined for a floating point
operand)], the result is the reciprocal of the result using the absolute
value of N as the exponent.

11.a

12

{*Constraint_Error (raised
by failure of run-time check)*} The implementation
of exponentiation for the case of a negative exponent is allowed to raise
Constraint_Error if the intermediate result of the repeated multiplications
is outside the safe range of the type, even though the final result (after
taking the reciprocal) would not be. (The best machine approximation
to the final result in this case would generally be 0.0.)

NOTES

13

19 {*Range_Check*
[partial]} {*check, language-defined
(Range_Check)*} As implied by the specification
given above for exponentiation of an integer type, a check is made that
the exponent is not negative. {*Constraint_Error (raised
by failure of run-time check)*} Constraint_Error
is raised if this check fails.

13.a.1/1

{*8652/0100*}
__{__*inconsistencies with Ada 83*} The definition
of "**" allows arbitrary association of the multiplications
which make up the result. Ada 83 required left-to-right associations
(confirmed by AI83-00137). Thus it is possible that "**" would
provide a slightly different answer in Ada 95 than in the same Ada 83
program.

13.a

We now show the specification
for "**" for integer types with a parameter subtype of Natural
rather than Integer for the exponent. This reflects the fact that Constraint_Error
is raised if a negative value is provided for the exponent.