Ada Programming/Attributes/'Unbiased Rounding

Description

X'Unbiased_Rounding(Y) is an Ada attribute where X is any floating-point type and Y is any instance of that type. This attribute represents the closest integer value to Y. If Y is exactly between two integer values (e.g. 1.5), then the result is the even value (e.g. 2.0).

Example

X : Float := 1.5;
Y : Float := 1.0;
Z : Float := 1.999;
... 
pragma Assert(Float'Unbiased_Rounding(X) = 2.0);  -- OK
pragma Assert(Float'Unbiased_Rounding(Y) = 1.0);  -- OK
pragma Assert(Float'Unbiased_Rounding(Z) = 2.0);  -- OK
pragma Assert(Float'Unbiased_Rounding(X) = 1.0);  -- Wrong
...
X := 2.5;
pragma Assert(Float'Unbiased_Rounding(X) = 2.0 );  -- OK
pragma Assert(Float'Unbiased_Rounding(X) = 3.0 );  -- Wrong

See also

Wikibook

• Ada Programming
• Ada Programming/Attributes
• Ada Programming/Attributes/'Ceiling
• Ada Programming/Attributes/'Floor
• Ada Programming/Attributes/'Rounding

Ada Reference Manual

• 13.3 Operational and Representation Attributes (Annotated)
• Annex K Language-Defined Attributes (Annotated)