Ada Programming/Keywords/delta

Ada. Time-tested, safe and secure.
Ada. Time-tested, safe and secure.

Description edit

This keyword is used in the declaration of fixed point types. Delta represents the absolute error bound of a fixed point type; that is, delta gives a hint to the compiler how to choose the smallest incremental value of the type, called the Small of the type. This Small value is accessible via the attribute T'Small.

For Ordinary fixed point types, it is by default a power of two not greater than the delta; it is specifyable by an attribute clause to be any value not greater than the delta.

For decimal fixed point types, the Small value is equal to the delta, which of course must be a power of ten.

Example edit

type Fixed_Point is delta 0.01 digits 10;  -- A decimal fixed point type
My_Fixed_Point : Fixed_Point := 0.0;
My_Fixed_Point := 0.1;   -- Ok
My_Fixed_Point := 0.02;  -- Ok
My_Fixed_Point := 0.001; -- Oops - this value is too small.
                         -- It will be represented by zero.

See also edit

Wikibook edit

Ada Reference Manual edit

Ada Quality and Style Guide edit

Ada Keywords
abort else new return
abs elsif not reverse
abstract (Ada 95) end null
accept entry select
access exception of separate
aliased (Ada 95) exit or some (Ada 2012)
all others subtype
and for out synchronized (Ada 2005)
array function overriding (Ada 2005)
at tagged (Ada 95)
generic package task
begin goto pragma terminate
body private then
if procedure type
case in protected (Ada 95)
constant interface (Ada 2005) until (Ada 95)
is raise use
declare range
delay limited record when
delta loop rem while
digits renames with
do mod requeue (Ada 95) xor