On 7 July 2016 at 12:57, Kacper Gutowski <mwgam...@gmail.com> wrote: > On 7 July 2016 at 12:55, Jay Foad wrote: > > (⊂+/3 4 ⍴ 5 6)≡3 4 +.⍴ 5 6 > > 1 > > Ah, I see what you mean. But it still wasn't my error, it's really what > ISO says. It's not equivalent to APL2 definition, nor to Dyalog's one, > and it seems to be wrong altogether. >
Which bit of ISO XAPL are you looking at? 9.3.2 Inner Product says: Z ← A f . g B Informal Description: Z is an array of shape (⍴A)[⍳0⌈¯1+⍴⍴A],(⍴B)[1+⍳0⌈¯1+⍴⍴B]. The elements of Z are the results obtained from evaluating the expression f/XgY for all possible combinations of X and Y, where X is a vector-item along-axis ⍴⍴A of A and Y a vector-item along-axis one of B. So if A and B are vectors, Z is a scalar whose single item is f/AgB. Hence Z itself is ⊂f/AgB. Jay.
