On 27.07.2009 00:32, David A. Black wrote:

> This was a somewhat incomplete forward reference to my "flipped logic"
> version (see below).

Ah, thanks for the clarification!

> Instead of setting an array to all true and then setting certain ones
> to false, I prefer piggybacking on the fact that array values are nil
> by default, and set them to true selectively.

Absolutely.  I would consider though to use a different type of 
container because the sequence of prime numbers becomes sparse as soon 
as you reach reasonable large numbers.  So using a bit set (either 
directly or by using Integers) or a Hash seems more appropriate.

Kind regards

	robert

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