Counting Prime Numbers: Sieve of Eratosthenes using Java

Hello readers. Hope you all had a good week.

New results:
Sieve

Old results:
CountPrime 5000 = 669 (Result in 10 seconds)
CountPrime 10000 = 1229 (Result in 85 seconds)

Last week I described here how to count prime numbers in a range using a rather unorthodox method called Hardy-Wright method. But as that method involves calculating factorials of all the numbers in the range [3..n], it is rather slow even when using multi-threading using a 8 core CPU.

So this week I was looking for a fast method to do this thing. I googled a bit and came across a method called Sieve of Eratosthenes.

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Mukul Debnath February 28, 2016

count prime / count prime numbers / prime / Sieve of Eratosthenes /

Counting Prime Numbers – Java SE Multi Threaded using BigInteger

Hope everybody enjoyed a good weekend.

So, this weekend I was going through the Programming Praxis website, and this problem caught my eye.

Prime numbers, they are a fascinating subject for mathematicians for several centuries now. Although there are other and faster methods of counting prime numbers up to a range, this method involves some rather unique programming techniques, like using very big numbers, looping through large mathematical range in parallel etc.
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Mukul Debnath February 21, 2016

BigInteger / count prime / count prime numbers / Hardy-Wright method / multi-threading / praxis solution / prime / Wilson’s Theorem /