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Vol.26 No.4

Vol.26 No.4


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British APL Association
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Volume 24, No.4

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Bring something beautiful

Roger Hui

The following e-mail exchange took place on 2010-06-24 during a discussion on numeric representation.

Morten Kromberg: And… I shall fight against adding any form of NaN / Infinity – to the death! They will horribly complicate our implementation and don’t help users do anything useful.

Roger Hui: In the year 2033 Earth was discovered by Survey Fleet MCXII of the Galactic Empire. The Emperor ordered Earth to send a representative to the court, with strict instructions to “bring something beautiful”.

What beautiful things does Earth have?
Earth Representative
Your excellency, our mathematician Euler proved in our year 1737 that +/(1+⍳∞)*-s ←→ ×/÷1-(⍭⍳∞)*-s
What is the symbol?
Earth Rep.
⍭i is the i-th prime.
And what is ∞? Does it do anything useful?
Earth Rep.
It denotes infinity, your excellency.
(ponders equation for a minute or two) Respect!
Neat notation you have there. Tell me more.
Earth Rep.
Your excellency, it’s called APL. It was invented by the Canadian Kenneth E. Iverson…


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