in reply to RE: RE: sieve of erothenes
in thread sieve of erothenes
Very slick! I've never seen it done like this before.
We're not using the same algorithm, but for my own morbid
curiosity I benchmarked it against mine and ase's code.
I added the 'o' modifier to your regex to speed it up a bit.
and ended up with:#!usr/bin/perl -w use Benchmark; timethese(100,{ Maverick => sub { for (1..1000){ push @_,$_; for (@_[1..$#_-1]){ pop @_ && last if !($_[-1]%$_) } } #print join "\t", @_; }, Ase => sub { $v='1' x 1000; for(2..1000){ next if !vec($v,$_-1,8); for($q=$_*2;$q<1001;$q+=$_){ vec($v,$q-1,8)=0 } } #print join "\t",grep {vec($v,$_-1,8)} (1..100 +0); }, Alan => sub { for(1..1000){ push @_,$_ if (1 x $_) !~ /^1?$|^(11+? +)\1+$/o } #print join "\t", @_; } });
You have the shortest but ase still has the fastest. :)Benchmark: timing 100 iterations of Alan, Ase, Maverick... Alan: 93 wallclock secs (92.95 usr + 0.00 sys = 92.95 CPU) Ase: 1 wallclock secs ( 1.03 usr + 0.00 sys = 1.03 CPU) Maverick: 1 wallclock secs ( 1.65 usr + 0.01 sys = 1.66 CPU)
This started off being about the seive of "the always mispelled guy", but now I'm curious about other ways of doing this. Perhaps on some rainy afternoon I'll go dig up few more interesting snippets to throw at the monk collective...
/\/\averick
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Cool Uses for Perl