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Re: [Bug-apl] an other inner product ,., bug

From: Juergen Sauermann
Subject: Re: [Bug-apl] an other inner product ,., bug
Date: Mon, 21 May 2018 15:33:29 +0200
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Hi Jay,

I believe that when they wrote the ISO standard they were still used to the old APL, where
f and g had to be scalar functions and then f/A g B of two vectors would anyhow be a scalar,
and therefore they simply forgot to enclose the result of
f/A g B.

/// Jürgen

On 05/21/2018 12:27 PM, Jay Foad wrote:
If you followed this part of the ISO standard verbatim then:

2 3 +.⍴ 4 5  ←→  +/2 3 ⍴ 4 5  ←→  13 14

GNU APL and APL2 actually return ⊂13 14 which seems more sensible. I am not sure why ISO has (or needs) that special case. It seems wrong to me.


On 18 May 2018 at 16:03, Juergen Sauermann <address@hidden> wrote:
The ISO standard follows suit, except that it has a special case for A and B being vectors:

"If A and B are both vectors, return f/A g B."   (ISO standard, page 121 with A=A1 and B=B1).

GNU APL follows the ISO standard

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