Task: write f explicitly.
f=:(0 ,.~ 0 ,. 0 ,~ 0 , ])^:[
We try substituting x and y for [ and ] .
g=: 13 :'(0 ,.~ 0 ,. 0 ,~ 0 , y)^:x'
2 g i. 2 3
|domain error: g
| (0,.~0,.0,~0,y) ^:x
We see failure with power.
We look up power in NuVoc
[x] u^:n y Fixed Power Conjunction
Oh! ^: requires a non-noun on its left (u) and a noun y to the right (n).
j computes (0 ,.~ 0 ,. 0 ,~ 0 , y) as a noun, and sure enough, domain error.
We might choose
g=: 13 :'(0 ,.~ 0 ,. 0 ,~ 0 , ])^:x y'
or
frame=: 13 :'(0 ,.~ 0 ,. 0 ,~ 0 , y)'
h=: 13 :'frame^:x y'
NB. successful tests, g and h match f.
(i.8) (g -: f)"0 _ i. 2 3
1 1 1 1 1 1 1 1
(i.8) (h -: f)"0 _ i. 2 3
1 1 1 1 1 1 1 1
At least, that's how I did it, and I probably shouldn't show this version
explicit_f =: dyad define
result =. y
for_repetition. i. x do.
a =. 0 , result
b =. a , 0
c =. b ,. 0
result =. 0 ,. c
end.
)
Date: Sun, 5 May 2019 07:36:11 +0000
From: Linda Alvord<[email protected]>
To:"[email protected]" <[email protected]>
Subject: Re: [Jprogramming] ambivalent tacit verb with Self-Reference
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Here's a simple function:
f=:(0 ,.~ 0 ,. 0 ,~ 0 , ])^:[
3 f i.3 4
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 1 2 3 0 0 0
0 0 0 4 5 6 7 0 0 0
0 0 0 8 9 10 11 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
But, oddly, I can't define this function explicitly.
Linda
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