Re: [FWP] Factorial Elegance

[Tim Ayers <tayers@bridge.com>]

>>>>> "a" == abigail  <abigail@foad.org> writes:
a> On Mon, Sep 18, 2000 at 11:49:02AM -0400, Josh Goldberg wrote:
>> my @cache = (1);
>> sub tayers {
>> my $x = shift;
>> @cache = (1);
>> return undef if $x < 0;
>> unless (defined $cache[$x]) {
>> my $p = $cache[$#cache];
>> $cache[$_] = $p *= $_ for ($#cache+1..$x);
>> }
>> return $cache[$x];
>> }

a> Well, as I said before, this routine is silly. It has a cache, but it's
a> written in such a way it cleans the cache each time. So, it's doing a
a> lot of useless work.

Obviously. The detrimental cache clearing was an artifact of various
benchmarking permutations. The original version that I sent to the
list did not have this bug. It's a shame that my flawed version is the
one that has propagated thru most of the thread.

Hope you have a very nice day, :-)
Tim Ayers (tayers@bridge.com)



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