Re: A86: Lookup tables
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Re: A86: Lookup tables
You need 256 x 256 entries for a * b. Then since a * b = b * a, skip half
of the entries. So you now need 256 x 256 / 2. Then you need all entries
for a = b. So total: (256 * 256 / 2) + 256 = 33024.
At 07:16 AM 6/4/98 -0400, you wrote:
>
>David Phillips wrote:
>
>> No, he is skipping half, plus adding on the duplicates, as he said earlier.
>>
>> At 08:58 PM 6/3/98 -0400, you wrote:
>> >
>> >Jimmy Mårdell wrote:
>> >
>> >> At 22:47 1998-06-02 EDT, you wrote:
>> >> >Wouldn't fetching the answer in itself involve multiplication? I'm
>> >> >having trouble thinknig of how to explain this, but how would you be
able
>> >> >to know where to look in the table without multiplication?
>> >>
>> >> No. It's not that easy though, if you decide to skip half of
>> >> the lookup table:
>> >>
>> >> 0 1 2 3 4 5 6 7 8 9
>> >> ---------------------------------
>> >> 0 0 0 0 0 0 0 0 0 0 0
>> >> 1 1 2 3 4 5 6 7 8 9
>> >> 2 4 6 8 10 12 14 16 18
>> >> 3 9 12 15 18 21 24 27
>> >>
>> >
>> >That's not skipping exactly half. You are skipping a little less than
half,
>> >but close enough. :)
>
>Ok. In a full table you would have a*b and b*a .. so you can skip b*a
because it
>is the same as a*b. But what happens when a=b? You have a*a and there is
only
>one entry for that, not two. So you can't skip those. That is what you mean
>right?
>
>--
>Bryan Rabeler <brabeler@ticalc.org>
> File Archives, HTML, and Support
> the ticalc.org project - http://www.ticalc.org/
>
>
>
// David Phillips
// mailto:electrum@tfs.net
// AIM: electrum32
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