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From: "Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org>
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Subject: Re: ada is getting spanked :(
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Date: 2006-10-29T02:26:50+00:00
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For the Nsieve problem, is there any reason not to do it like this:

-- The Great Computer Language Shootout
-- http://shootout.alioth.debian.org/
--
-- Contributed by Jim Rogers
-- Modified by Jeffrey R. Carter

with Ada.Command_Line;    use Ada.Command_Line;
with Ada.Text_IO;         use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;

procedure Nsieve is
    procedure Count (N : in Natural) is
       M : constant Natural := 2 ** N * 10_000;

       type Boolean_Array is array (2 .. M) of Boolean;

       M2 : constant Natural := M / 2;
       M3 : constant Natural := M2 / 2;

       C1 : Natural := 0;
       C2 : Natural := 0;
       C3 : Natural := 0;
       S : Boolean_Array := (others => True);
       I : Positive;
    begin -- Count
       for K in S'Range loop
          if S (K) then
             C1 := C1 + 1;
             I := K + K;

             if I <= M2 then
                C2 := C2 + 1;

                if I <= M3 then
                   C3 := C3 + 1;
                end if;
             end if;

             while I <= M loop
                if S (I) then
                   S (I) := False;
                end if;

                I := I + K;
             end loop;
          end if;
       end loop;

       Put ("Primes up to ");
       Put (Item => M, Width => 8);
       Put (" ");
       Put (Item => C1, Width => 8);
       New_Line;
       Put ("Primes up to ");
       Put (Item => M2, Width => 8);
       Put (" ");
       Put (Item => C2, Width => 8);
       New_Line;
       Put ("Primes up to ");
       Put (Item => M3, Width => 8);
       Put (" ");
       Put (Item => C3, Width => 8);
       New_Line;
    end Count;

    N : constant Natural := Natural'Value (Argument (1) );
begin -- Nsieve
    Count (N);
end Nsieve;

?

This is much faster (0.6 s on my machine, which gave about 1.8 s for the 
existing version), and should put us in 1st place.

-- 
Jeff Carter
"Your mother was a hamster and your father smelt of elderberries."
Monty Python & the Holy Grail
06