Just looking at the code: e.g. by replacing
(>:i.y)-.,(>:i.y)*/(y$q:y)
with
(1 + i.y) ([ -. [: , */) {. __ q: y
ending up with a tacit verb:
phi17=: [: (% ([: # (1 + i.) ([ -. [: , */) {.@q:~&__)"0)2+i.
ts 'P=.phi 2+i.1e3'
7.58904 9.48134e6
ts 'Q=.phi17 1e3'
0.111421 66816
P-:Q
1
-->
much faster and leaner.
Hallo David Vaughan, je schreef op 12-09-11 13:34:
> This verb is considerably slower than I was hoping - is there a particular
> part of it that would be a bottleneck, or that I've written naively?
>
> On 12 Sep 2011, at 03:19, bill lam wrote:
>
>> There was domain error becasue q: cannot take 0 as its argument. Similarly
>> q:1 will return an empty list so that your phi will raise errors even for
>> scalar 0 and 1.
>>
>> Пнд, 12 Сен 2011, David Vaughan писал(а):
>>> Hi,
>>>
>>> I have defined a verb like so:
>>>
>>> phi=: 3 : 'y%#(>:i.y)-.,(>:i.y)*/(y$q:y)'
>>>
>>> It seems I can only use with atoms, e.g.
>>>
>>> phi 6
>>> 3
>>>
>>> What I want to be able to do, is apply this verb to a list. I would also
>>> like to know how I can define verbs so they can be more flexible in this
>>> way in a general sense.
>>>
>>> This is the output of my failed attempt:
>>>
>>> phi i.6
>>> |domain error: phi
>>> | y%#(>:i.y)-.,(>:i.y)*/(y$ q:y)
>>>
>>> I can kind of see where the problems may be, but I can't think how to
>>> eradicate them - this is the sort of thing I would usually be just using
>>> loop for in a C type language, but I would dearly love to know the best J
>>> style approach. Also, I find that these error messages are difficult to
>>> interpret - I'm not clear where the error has been found, but I assume the
>>> large space has something to do with it (any advice here would be helpful).
>>>
>>> Thanks in advance.
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