« first day (1049 days earlier)      last day (1613 days later) » 

Feeds
Feeds
12:15 AM
Adám has added an event to this room's schedule.
 
Adám
Adám
@AntonioNikishaev @A̲̲ @Anand I've rescheduled this week's APL Cultivation to Thursday next week.
 
Feeds
Feeds
Adám has removed an event from this room's schedule.
 
 
4 hours later…
A̲̲
A̲̲
4:01 AM
APL has two different symbols for negation: ¯ (Negative constant) and - (Negation). Since a negative constant produces the same result as negation on a constant, why didn't they combine the two symbols into a single negation symbol?
 
Bubbler
Bubbler
4:18 AM
@A̲̲ One reason I'd guess is that APL doesn't have operator precedence. Without ¯, it'd take an extra parentheses to enter a negative constant in the middle of an expression.
And writing a vector having negative numbers e.g. 1(-2)3 vs. 1 ¯2 3
 
 
3 hours later…
Adám
Adám
7:46 AM
Plus and minus signs
The plus and minus signs (+ and −) are mathematical symbols used to represent the notions of positive and negative as well as the operations of addition and subtraction. Their use has been extended to many other meanings, more or less analogous. Plus and minus are Latin terms meaning "more" and "less", respectively. == History == Though the signs now seem as familiar as the alphabet or the Hindu-Arabic numerals, they are not of great antiquity. The Egyptian hieroglyphic sign for addition, for example, resembled a pair of legs walking in the direction in which the text was written (Egyptian could...
 
 
2 hours later…
Bubbler
Bubbler
10:00 AM
Can anyone crack this (apart from the datatype limits)?
 
Adám
Adám
10:49 AM
@Bubbler Hm, while valid in theory, the code can't actually run due to certain system limitations.
 
 
12 hours later…
PuercoPop
PuercoPop
10:43 PM
Hi, I'm trying to understand how (¯2≡/⊢) works. From reading aplcart.info it appears (¯2 op /⊢) is an idiom to apply op to successively on each element and its predecessor. However I'm at a loss as to how it works. especially the ¯2. Any tips?
 
Adám
Adám
@PuercoPop Have you tried experimenting with it? Maybe try using a different function than ≡
 
Bubbler
Bubbler
@PuercoPop From the docs:
> If X is negative, each sub-vector is reversed before being reduced.
 
Adám
Adám
⎕←2,/'abcd'
 
Dyalog APL
Dyalog APL
@Adám
┌──┬──┬──┐
│ab│bc│cd│
└──┴──┴──┘
 
PuercoPop
PuercoPop
Yeah, <, > and even applying it twice in succession so try to detect 'triples'
 
Adám
Adám
10:54 PM
⎕←¯2,/'abcd'
 
Dyalog APL
Dyalog APL
@Adám
┌──┬──┬──┐
│ba│cb│dc│
└──┴──┴──┘
 
Adám
Adám
⎕←2{⍺,'≡',⍵}/'abcd'
 
Dyalog APL
Dyalog APL
@Adám
┌───┬───┬───┐
│a≡b│b≡c│c≡d│
└───┴───┴───┘
 
Adám
Adám
⎕←¯2{⍺,'≡',⍵}/'abcd'
 
Dyalog APL
Dyalog APL
@Adám
┌───┬───┬───┐
│b≡a│c≡b│d≡c│
└───┴───┴───┘
 
PuercoPop
PuercoPop
10:56 PM
@Adám This is what I needed. Thanks.
 
Bubbler
Bubbler
So ¯2 f/ x is equivalent to 2 f⍨/ x
 
PuercoPop
PuercoPop
@Bubbler I haven't seen ⍨ yet
 
Adám
Adám
@Bubbler True, but only for 0, 1, and 2. Generally not for 3 and higher.
@PuercoPop X f⍨ Y is Y f X
 
Bubbler
Bubbler
11:55 PM
Just found dfns.words and dfns.segs, which seem to be super-handy when dealing with AoC inputs
 

« first day (1049 days earlier)      last day (1613 days later) »