Re: [FWP] Factorial Elegance

[abigail@foad.org]

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];
>     }

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

>     sub abigail {
>         my ($r  => $x) = (1, shift);
>         do {$r *=  $x} while $x -- > 2;
>         $r;
>     }
> 
> sub josh {
>   my $x=shift;
>   my $l=$x;
>   while ($l>1){$x*=--$l};

Why spend time multiplying something with 1? 

    while ($l > 2) {$x *= --$l}

ought to be slightly faster.

>   $x;
> }


Abigail

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