Re: [FWP] Fun With Golf - digital roots

[Ian Phillipps <igp_list2@tesco.net>]

[I think the FWP list processor mangles the Reply-To: header, which read
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On Wed, 18 Oct 2000 at 12:48:21 -0400, Ronald J Kimball wrote:
> On Wed, Oct 18, 2000 at 12:37:45PM -0400, yanick1@sympatico.ca wrote:
> > perlgolf hole - Digital Root

> > Write a subroutine to compute the digital root of any whole number argument.
> > Winner: sub hole {$_=pop;1while s/(\d)(\d)/$1+$2/ge;$_}

I didn't know what a digital root was until Google pointed me to
http://mathworld.wolfram.com/DigitRoot.html, but using the info on that
page, I submit:

            sub hole {$_[0]&&($_[0]-1)%9+1}

or this if you allow it to modify its parameter:

            sub hole {$_[0]&&$_[0]--%9+1}

Neither this nor yanick1's submission behave correctly for negative
numbers, whatever "correctly" means here.

Ian

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