The ISO spec doesn't address what the index-of function should do when the left argument is not a scalar or a one-dimensional array.
GNU APL extends this, but I don't really understand in what way. How am I to interpret the output from this? * (2 2 ⍴ 104 105 106 107) ⍳ (3 4 ⍴ 100+⍳100)* ┏→━━━━━━━━━━━━━━━━━━━━━━┓ ↓┏⊖┓ ┏⊖┓ ┏⊖┓ ┏⊖┓ ┃ ┃┃0┃ ┃0┃ ┃0┃ ┃0┃ ┃ ┃┗━┛ ┗━┛ ┗━┛ ┗━┛ ┃ ┃┏→━━┓ ┏→━━┓ ┏→━━┓ ┏→━━┓┃ ┃┃0 0┃ ┃0 1┃ ┃1 0┃ ┃1 1┃┃ ┃┗━━━┛ ┗━━━┛ ┗━━━┛ ┗━━━┛┃ ┃┏⊖┓ ┏⊖┓ ┏⊖┓ ┏⊖┓ ┃ ┃┃0┃ ┃0┃ ┃0┃ ┃0┃ ┃ ┃┗━┛ ┗━┛ ┗━┛ ┗━┛ ┃ ┗∊━━━━━━━━━━━━━━━━━━━━━━┛ Regards, Elias
