Re: [MacPerl] Prime Numbers

[bart.lateur@skynet.be (Bart Lateur)]

On Mon, 16 Aug 1999 11:53:57 -0500 (CDT), Matthew Langford wrote:

>What is an obvious (brute force) way of testing for primes?  Isn't it to
>try dividing by all the numbers less than it?

>That is what this algorithm does, only it is using the pattern matching
>engine to do all the work.

So a different algorithm should be able to give a large speed boost. For
example (also crude, but a lot faster):

 - Try to divide by all primes found so far (except 1).

 - You never need go beyond sqrt(number). If it has a factor larger than
sqrt(number), it must have a factor below it too.

 - Apart from 2, you needn't test any even numbers.

	Bart.

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