#!/usr/bin/perl -w
BEGIN { unshift @INC, '../lib'; } # uncomment to use old, org version
$| = 1;
use Math::BigInt;
# this is a complicated version of the prime number sieve.
# It is not optimized (since we want to benchmark as many features as
# possible).
$amount = Math::BigInt->new( shift || 1000000 );
@primes = (1,1,0); # any not defined number is prime, 0,1 are not, but 2 is
my $prime = Math::BigInt->new (3); # start
# the loop below is faster in the old version than in the new, since it is
# the worst case for new lib: small numbers and lot's of bstr()/new().
# It also slows down the benchmark too much so we use slightly faster int here
$r = 0; my $a = $amount->numify();
for ($i = 3; $i < $a; $i++) # int version
{
$primes[$i] = $r; $r = 1-$r;
}
# find primes
OUTER:
while ($prime < $amount)
{
# find first unmarked, it is the next prime
$cur = $prime;
while ($primes[$cur])
{
$cur += 2; last OUTER if $cur >= $amount; # no more to do
}
# $cur is now new prime
$str = "$cur"; $str =~ s/\+//; # unify output for comapre
#print "$str $prime $amount\n";
# now strike out all multiples of $cur
$add = $cur*2;
$prime = $cur + 2; # next round start two higher
$cur += $add;
while ($cur < $amount)
{
$primes[$cur] = 1; $cur += $add;
}
}
$i = 0;
foreach (@primes)
{
push @real_primes, $i if $primes[$i] == 0;
$i++;
}
# uncomment to print em:
# foreach (@real_primes) { print "$_\n"; }
print "last prime: $real_primes[-1]\n";
# check against text
open FILE, '1000.txt' or die "Can't read 1000.txt: $!";
my @test;
while ()
{
next if /^#/;
next if /^\s*$/;
$_ =~ s/\s+/ /g;
$_ =~ s/^\s+//;
$_ =~ s/\s+$//;
push @test, split /\s+/,$_;
}
close FILE;
my $i = 0;
foreach (@real_primes)
{
print "oups: $i: $test[$i] != $real_primes[$i]\n"
if $test[$i] != $real_primes[$i]; $i++;
last if $i >= 1000;
}
print "done\n";