http://i.imgur.com/7vMrDan.jpg
?(3⍴5) (2 3⍴10) DOMAIN ERROR ?(3⍴5)(2 3⍴10) ^^ (3⍴5) (2 3⍴10) 5 5 5 10 10 10 10 10 10 ?(3⍴5) 5 3 4 ?(2 3⍴10) 9 6 5 5 10 7 ?(3⍴5) 30 DOMAIN ERROR ?(3⍴5)30 ^^ In MicroAPL, this supposedly works, as is indicated by the documentation here http://www.microapl.co.uk/apl_help/ch_020_020_170.htm -- last example --