[33018] in Perl-Users-Digest
Perl-Users Digest, Issue: 4294 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Oct 15 16:09:21 2014
Date: Wed, 15 Oct 2014 13:09:04 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 15 Oct 2014 Volume: 11 Number: 4294
Today's topics:
prime <gravitalsun@hotmail.foo>
Re: prime <jurgenex@hotmail.com>
Re: prime <gravitalsun@hotmail.foo>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 15 Oct 2014 21:46:22 +0300
From: George Mpouras <gravitalsun@hotmail.foo>
Subject: prime
Message-Id: <m1mfe9$15s6$1@news.ntua.gr>
# can this be any faster ;
use strict; use warnings; use feature qw/say/;
use Time::HiRes; my $time_start = [ Time::HiRes::time ];
say "Found primes : ", Find_the_prime_numbers_upto(20_000);
say "Seconds : ", Time::HiRes::tv_interval($time_start, [
Time::HiRes::time ]);
sub Find_the_prime_numbers_upto
{
return if $_[0] < 2;
my ($found, $ok, $number)=(1,1,1); #say 2;
for (1 .. int ($_[0]-1)/2)
{
$number = 2*$_ + 1;
$ok=1;
for (2 .. $number-1)
{
if (0 == $number % $_)
{
$ok=0;
last
}
}
$found++ if $ok; # say $number if $ok
}
$found
}
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Date: Wed, 15 Oct 2014 11:56:10 -0700
From: Jürgen Exner <jurgenex@hotmail.com>
Subject: Re: prime
Message-Id: <dlgt3a1ftpsn728fdror5478885hf2nmus@4ax.com>
George Mpouras <gravitalsun@hotmail.foo> wrote:
># can this be any faster ;
[...]
>sub Find_the_prime_numbers_upto
[simple-minded implementation of prime search algorithm snipped]
Yes. The Sieve of Eratosthenes is significantly faster.
jue
------------------------------
Date: Wed, 15 Oct 2014 22:32:32 +0300
From: George Mpouras <gravitalsun@hotmail.foo>
Subject: Re: prime
Message-Id: <m1mi4r$1c2a$1@news.ntua.gr>
On 15/10/2014 9:56 μμ, jurgenex@hotmail.com wrote:
> George Mpouras <gravitalsun@hotmail.foo> wrote:
>> # can this be any faster ;
> [...]
>> sub Find_the_prime_numbers_upto
> [simple-minded implementation of prime search algorithm snipped]
>
> Yes. The Sieve of Eratosthenes is significantly faster.
>
> jue
>
4.4 seconds upto 10_000_000 , impressive !
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
Administrivia:
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End of Perl-Users Digest V11 Issue 4294
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