Approximate equality: Difference between revisions

=={{header|Ada}}==

<lang Ada>

with Ada.Text_IO; use Ada.Text_IO;

with Ada.Numerics.Generic_Elementary_Functions;

procedure Main is

type Real is digits 18;

package Real_Funcs is new Ada.Numerics.Generic_Elementary_Functions(Real);

use Real_Funcs;

package Real_IO is new Ada.Text_IO.Float_IO(Real);

use Real_IO;

function Approx_Equal (Left : Real; Right : Real) return Boolean is

-- Calculate an epsilon value based upon the magnitude of the

-- maximum value of the two parameters

eps : Real := Real'Max(Left, Right) * 1.0e-9;

begin

if left > Right then

return Left - Right < eps;

else

return Right - Left < eps;

end if;

end Approx_Equal;

Type Index is (Left, Right);

type Pairs_List is array (Index) of Real;

type Pairs_Table is array(1..8) of Pairs_List;

Table : Pairs_Table;

begin

Table := ((100000000000000.01, 100000000000000.011),

(100.01, 100.011),

(10000000000000.001 / 10000.0, 1000000000.0000001000),

(0.001, 0.0010000001),

(0.000000000000000000000101, 0.0),

(sqrt(2.0) * sqrt(2.0), 2.0),

(-sqrt(2.0) * sqrt(2.0), -2.0),

(3.14159265358979323846, 3.14159265358979324));

for Pair of Table loop

Put(Item => Pair(Left), Exp => 0, Aft => 16, Fore => 6);

Put(" ");

Put(Item => Pair(Right), Exp => 0, Aft => 16, Fore => 6);

Put_Line(" " & Boolean'Image(Approx_Equal(Pair(Left), Pair(Right))));

end loop;

end Main;

</lang>

{{Output}}

<pre>

100000000000000.0100000000000000 100000000000000.0110000000000000 TRUE

100.0100000000000000 100.0110000000000000 FALSE

1000000000.0000001000000000 1000000000.0000001000000000 TRUE

0.0010000000000000 0.0010000001000000 FALSE

0.0000000000000000 0.0000000000000000 FALSE

2.0000000000000000 2.0000000000000000 TRUE

-2.0000000000000000 -2.0000000000000000 FALSE

3.1415926535897932 3.1415926535897932 TRUE

</pre>