Comments on: The Sieve of Eratosthenes in C# http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/ With a hint of Social Ineptitude Tue, 07 Feb 2012 09:05:01 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Torleif http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-5872 Torleif Sun, 03 Apr 2011 14:37:12 +0000 http://www.geekality.net/?p=626#comment-5872 Oh really? Interesting. Maybe I might have to create a new post then with the real one, hehe. I thought this was pretty much the same, but I see your point! Thanks for the out-pointing :) Do you have a good primality you can suggest? Have looked into that a bit, but found the whole thing a bit confusing. Seemed most of those tests didn't really prove it's a prime, but rather tell you it might be? And for generating a series of primes that seemed a bit risky... Oh really? Interesting. Maybe I might have to create a new post then with the real one, hehe. I thought this was pretty much the same, but I see your point! Thanks for the out-pointing :)

Do you have a good primality you can suggest? Have looked into that a bit, but found the whole thing a bit confusing. Seemed most of those tests didn’t really prove it’s a prime, but rather tell you it might be? And for generating a series of primes that seemed a bit risky…

]]> By: Daniel http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-5852 Daniel Sat, 02 Apr 2011 15:00:50 +0000 http://www.geekality.net/?p=626#comment-5852 I must point out this isn't actually the Sieve of Eratostenes but trial division by primes. By definition, a sieve takes a finite set of numbers and eliminates elements of the set. In contrast, you are grabbing the next odd number and checking its primality via trial division. If you would like to increase the efficiency of your algorithm, may I suggest you use a more efficient primality test: http://en.wikipedia.org/wiki/Prime_number#Primality_testing_vs._primality_proving I must point out this isn’t actually the Sieve of Eratostenes but trial division by primes. By definition, a sieve takes a finite set of numbers and eliminates elements of the set. In contrast, you are grabbing the next odd number and checking its primality via trial division. If you would like to increase the efficiency of your algorithm, may I suggest you use a more efficient primality test: http://en.wikipedia.org/wiki/Prime_number#Primality_testing_vs._primality_proving

]]> By: Torleif http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-2774 Torleif Tue, 07 Dec 2010 12:51:04 +0000 http://www.geekality.net/?p=626#comment-2774 :D :D

]]> By: Gregory LEOCADIE http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-2773 Gregory LEOCADIE Tue, 07 Dec 2010 12:44:10 +0000 http://www.geekality.net/?p=626#comment-2773 mine... Damn it...I should be more careful... Ok, I learned 2 things: - if a modification occurs in a copy/past code, check the my mouth before speaking - LINQ is good :D mine…
Damn it…I should be more careful…
Ok, I learned 2 things:
- if a modification occurs in a copy/past code, check the my mouth before speaking
- LINQ is good :D

]]> By: Torleif http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-2769 Torleif Tue, 07 Dec 2010 11:47:45 +0000 http://www.geekality.net/?p=626#comment-2769 In yours or mine? Cause I cast the result of the sqrt to a ulong, so there shouldn't be any comparisons between double and ulong. Unless I'm missing something here... In yours or mine? Cause I cast the result of the sqrt to a ulong, so there shouldn’t be any comparisons between double and ulong. Unless I’m missing something here…

]]> By: Gregory LEOCADIE http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-2764 Gregory LEOCADIE Tue, 07 Dec 2010 07:57:25 +0000 http://www.geekality.net/?p=626#comment-2764 It seems that my version is a little bit faster (I'll do more tests). I think that the comparison in the TakeWhile (double against ulong) is the culprit (the compiler has to generate more code to handle it). It seems that my version is a little bit faster (I’ll do more tests). I think that the comparison in the TakeWhile (double against ulong) is the culprit (the compiler has to generate more code to handle it).

]]> By: Gregory LEOCADIE http://www.geekality.net/2009/10/19/the-sieve-of-eratosthenes-in-c/#comment-2763 Gregory LEOCADIE Tue, 07 Dec 2010 07:02:49 +0000 http://www.geekality.net/?p=626#comment-2763 Oh good point. It was just another way, and not so good after all. I'll make some benchmarks ;) Oh good point. It was just another way, and not so good after all.
I’ll make some benchmarks ;)

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