<"2 ] 3 kfaces C
|length error: kfaces
| ,/(({.y)+"1({:y)*"1 (#^:_1"1#:@i.@(2^+/))"1 id),:"1({:y)*"1-.id
3-face of the cube should be included as well.
A simpler alternative:
kfcs=: 3 : 0
t1=. t=. #:i.2^{:$y
;(<y) (*"1&{: ,:~"1 {...@] +"1 }:@[ *"1 {:@] )~&.> t1 <@([ ,~ ] #~ 0 =
+/@:*"1)"1 _ t
:
t1=. (#~ x = +/"1 ) t=. #:i.2^{:$y
y (*"1&{: ,:~"1 {...@] +"1 }:@[ *"1 {:@] )~"2 t1 ([ ,~ ] #~ 0 = +/@:*"1)"1 _
t
)
<"2 ] 0 kfcs C
+-----+------+-----+------+-----+------+-----+------+
|4 3 0|4 3 _2|4 0 0|4 0 _2|0 3 0|0 3 _2|0 0 0|0 0 _2|
|0 0 0|0 0 0|0 0 0|0 0 0|0 0 0|0 0 0|0 0 0|0 0 0|
+-----+------+-----+------+-----+------+-----+------+
<"2 ] 1 kfcs C
+------+-------+------+-------+
|4 3 0|4 0 0 |0 3 0|0 0 0 |
|0 0 _2|0 0 _2 |0 0 _2|0 0 _2 |
+------+-------+------+-------+
|4 3 0|4 3 _2|0 3 0|0 3 _2|
|0 _3 0|0 _3 0|0 _3 0|0 _3 0|
+------+-------+------+-------+
| 4 3 0| 4 3 _2| 4 0 0| 4 0 _2|
|_4 0 0|_4 0 0|_4 0 0|_4 0 0|
+------+-------+------+-------+
<"2 ] 2 kfcs C
+-------+--------+
|4 3 0|0 3 0 |
|0 _3 _2|0 _3 _2 |
+-------+--------+
| 4 3 0| 4 0 0 |
|_4 0 _2|_4 0 _2 |
+-------+--------+
| 4 3 0| 4 3 _2|
|_4 _3 0|_4 _3 0|
+-------+--------+
<"2 ] 3 kfcs C
+--------+
| 4 3 0|
|_4 _3 _2|
+--------+
faces are ordered to their diagonal vector.
Without left argument, all faces are given:
$ kfcs C
27 2 3
For higher dimensions:
2 (kfcs -:&(,@:(<"2)) kfaces) 4 3 0 _2,:_4 _3 _2 1
1
$ kfcs 4 3 0 _2,:_4 _3 _2 1
81 2 4
R.E. Boss
> -----Oorspronkelijk bericht-----
> Van: [email protected] [mailto:programming-
> [email protected]] Namens Andrew Nikitin
> Verzonden: vrijdag 9 april 2010 22:01
> Aan: J programming
> Onderwerp: Re: [Jprogramming] boxes
>
>
> > From: Kip Murray
> >
> > Andrew, Oleg's dyadic verb faces below works correctly on my example
> > 4 3 0 ,: _4 _3 _2 -- try
> >
> > <"_1 [ 4 3 0 faces _4 _3 _2
> >
> > -- and Oleg claims his faces works in all dimensions, see his examples
> below.
> >
>
> I Olegs verb returns (n-1) dimensional faces of n-dimensional boxes.
> I meant k dimensional faces of n-dimensional boxes.
> For regular cube 2-face is what normally called "face", 1-face is an edge
> and
> 0-face is a vertex.
>
> require 'statfns'
> kfaces=:4 : 0"0 2
> n=.{:$y
> k=.x
> id=.(i.n) (e."1) (n-k) comb n
> ,/(({.y) +"1 ({:y) *"1 (#^:_1"1 #:@i.@(2 ^ +/))"1 id) ,:"1 ({:y) *"1 -
> .id
> )
>
> C=.4 3 0 ,: _4 _3 _2
> <"2 ] 0 kfaces C
> ------T------T-----T------T-----T------T-----T------┐
> │4 3 0│4 3 _2│4 0 0│4 0 _2│0 3 0│0 3 _2│0 0 0│0 0 _2│
> │0 0 0│0 0 0│0 0 0│0 0 0│0 0 0│0 0 0│0 0 0│0 0 0│
> L-----+------+-----+------+-----+------+-----+-------
> <"2 ] 1 kfaces C
> -------T------T------T------T------T-------T------T-------T------T-------T
> ------T-------┐
> │4 3 0│4 0 0│0 3 0│0 0 0│4 3 0│4 3 _2│0 3 0│0 3 _2│ 4 3 0│ 4 3 _2│
> 4 0 0│ 4 0 _2│
> │0 0 _2│0 0 _2│0 0 _2│0 0 _2│0 _3 0│0 _3 0│0 _3 0│0 _3 0│_4 0 0│_4 0
> 0│_4 0 0│_4 0 0│
> L------+------+------+------+------+-------+------+-------+------+-------+
> ------+--------
> <"2 ] 2 kfaces C
> --------T-------T-------T-------T-------T--------┐
> │4 3 0│0 3 0│ 4 3 0│ 4 0 0│ 4 3 0│ 4 3 _2│
> │0 _3 _2│0 _3 _2│_4 0 _2│_4 0 _2│_4 _3 0│_4 _3 0│
> L-------+-------+-------+-------+-------+---------
>
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