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ngn
10:16 AM
is there a rational explanation for 0 1⊥n ←→ 2×n?
 
@ngn Extension of ⍵
⍞←0 0 0 1⊥123 123 123 123
 
@Adám 246
 
⎕←0 60 60⊥0 1 30 ⋄
⎕←(1,⍨⌽×\⌽1↓0 60 60)+.×0 1 30
 
@Adám
90
90
 
⎕←0 0 1⊥123 ⋄
⎕←(1,⍨⌽×\⌽1↓0 0 1)+.×123
 
10:22 AM
@Adám
246
246
 
@ngn ^ ^^ etc,
 
ngn
@Adám got it, thanks
 
 
13 hours later…
11:51 PM
Announcement: APLcart finally includes all* of the famous FinnAPL idiom list, fully updated to use modern APL.
* Well, except the following 13 entries, because I don't understand them. I'd much appreciate anyone's explaining one or more to me:
BA2∧A=⌈\BA1×A←+\BA2>¯1↓0,BA2                               Groups of ones in BA2 pointed to by BA1 (or trailing parts).
BV2∧A∊(BV1∧BV2)/A←+\BV2>¯1↓0,BV2                           Groups of ones in BV2 pointed to by BV1.
⎕IO+(⍴NM)⊤-⎕IO-(,(NM=(⍴NM)⍴⌈⌿NM)∧NM=⍉(⌽⍴NM)⍴⌊/NM)/⍳×/⍴NM   Index pairs of saddle points.
(0,⍳(⍴XV)-IS)∘.+IS                                         Moving index of width IS for vector XV.
+/A∧⍉A←NV1∘.≤NV2                                           Number of ?s intersecting ?s (NV1=starts, NV2=stops).
 

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