I was wrong. Ambrus's is faster than mine.
foo =: ((~:>:)*>+])i.
timer '3 foo 10'
2.38037e_5
And it's in the spirit of what I felt was possible. Thanks Ambrus.
On Sun, May 1, 2011 at 3:09 PM, Zsbán Ambrus <[email protected]> wrote:
> On Fri, Apr 29, 2011 at 2:03 PM, Ian Clark <[email protected]> wrote:
>> My brain's a mess this morning...
>>
>> Let foo be a dyadic verb which simply returns i.y with the zero
>> floated up to position x .
>> (Forget the cases of x<1 and x>y)
>>
>> foo=: 4 : '(1|.i.x) , (x}.i.y)'
>> 3 foo 9
>> 1 2 0 3 4 5 6 7 8
>
> Everyone seems to be giving answers that use amends or takes and drops
> or even permute. Why, if we can manage this easily with only the
> operators our fathers have had, that is, iota, comparisions, and
> arithmetic. :-)
>
> foo =: ((~:>:)*>+])i.
> 3 foo 9
> 1 2 0 3 4 5 6 7 8
>
> Or, if you also want to abstain from forks and use only delta-defined
> verbs, then here's the explicit form.
>
> foo =: 4 :'(x~:1+z)*z+x>z=.i.y'
> 3 foo 9
> 1 2 0 3 4 5 6 7 8
>
> Ambrus
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