In the Beginning

⌊ floor ⌈ ceiling ⍟ log

⌊ and ⌈ were punnish when the notation was introduced in 1962. They have long since gone mainstream, used even by respectable mathematicians and computer scientists.

To see why ⍟ is a pun, see the Vector article My Favourite APL Symbol.

• • • • •

The following are a joint effort by the Dyalog team, many derived after a sumptuous dinner and a few glasses of wine. Column 0 are valid APL expressions. For an enhanced experience may we suggest covering column 1 as you read column 0 for the first time.

In Modern Times

⊃⎕A~'L' the first no el ⍴⍴⍴'your boat' rho rho rho your boat *⍣¯1⊢fly+fly log of the flies {⍺←23 ⋄ (2÷(○1)*0.5)×-/⍵×(⍵*2×⍳⍺)÷

(!⍳⍺)×1+2×⍳⍺}ghanistan erf ghanistan ↑^≡ mix and match >/+/∘⎕UCS¨'the parts' 'the whole' the sum of the parts is greater than the whole ?⍨2e9 a big deal ○1 APL π 2(⌷⍤1)2 3 4⍴○1 a slice of APL π 0 0⍉3 4⍴○1 another slice of APL π easy←○1 easy as π {4×-/÷1+2×⍳⍵}1e6 a π long in the making ↑ pike; see APL Quotations and Anecdotes ↓ spike ⍋ pine ⍒ spine ⍋ Concorde taking (and showing) off ⍒ uh-oh {⍵⌷⍨⊂?⍨≢⍵} degrade bb∨~bb two b or not two b bb≥bb two b or not two b ×× sign of the times a←2÷⍨3 4⍴⍳12 ⋄ *○0j1×a show off a←2÷⍨3 4⍴⍳12 ⋄ *○0j1×a+2e9 shameless show off ⍎turtles←'⍎turtles' it’s turtles all the way down…

In Honour of a Certain Movie Series

0⍴'menace' I. The Empty Menace ⊢⎕ns¨ 2⍴⎕this II. Tack of the Clones ⌽'htxiS'~'x' III. Reverse of the Sith ⎕io←~⎕io IV. A New Beginning {'Jedi'⊢1e3×○R} V. The M π R Strikes from the Back {'Jedi'} VI. Return Jedi (+⌿÷≢)3 4 5⊣⎕dl 10 VII. The Fork Awakens

may←+⌿÷≢ ⋄ may∘∪ may the fork be with you 0 1 2 3 (⌊/⍬) 5 6 the fourth is strong with this one 4 4 4 4 (⌊/⍬) 4 4 I feel a great disturbance in the fours 1=?2e9 this is not the number you are looking for 1=?2e9 in my experience, there’s no such thing as luck Luke.## I AM your father 4 ⊃ 0 1 2 3 'dark side' vier ist the path to the dark side x{0.5×⍵+⍺÷⍵}⍣≡darkside do not underestimate the power of the dark side ⎕ct←1 I find your lack of faith disturbing 0.2 ∊ ÷3 1 4 1 9 2 6 3 8 9 7 9 I find your lack of a-fifth disturbing {0::⍺⍺~⍵ ⋄ ⍺⍺ ⍵} do, or do not; there is no :Try