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Subject: Re: Hash table allocation

Author: Dieter Buerssner

Date: 14:43:59 08/27/03

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On August 27, 2003 at 17:28:23, Ricardo Gibert wrote:

Ricardo, I think we agree pretty much.

>This last remark about % is interesting. I hadn't thought about verification if
>the modulo method is used. I suppose you can use a 2nd modulus that is
>relatively prime to 1st. Or even better is to use the value of the quotient.

Indeed. Storing the quotient as the verification key, while using modulo for
calculating the index seems theoretically optimal (in practice, I think, it
would not perform better than the multiplication method - even when ignoring the
efficiences of mod compared to mul).

Probably there is no platform, that can do modulo/division (under the
circumstances we have here) similarily fast, than multiplication. But after all,
it is a rather accademic discussion. On my computer, the access to a random
memory location (assuming the range is large - much larger than any cache) takes
considerably more time, than the index calculation - whatever way you use.

Regards,
Dieter




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