[ummaycoc]

Do you have an explanation handle on the windowed reductions? Specifically what the number on the left means in this case (or in general)? I've tried it and it looks like `(n+1)</v` is basically `2</(n</v)` for `n>1` but I also see some things that don't exactly fit that pattern.

[mlochbaum]

The left argument is a window length. Windowed reduction groups the argument into overlapping windows with that length and does a reduction on each one of them. So if y has row length n, (n ?/ y) is the same as (?/ y) but the rank isn't reduced by one (there's an extra 1 at the end of the shape). For a numeric vector you can use ,/ as a windowed reduction to see the subvectors that are reduced over, but for a nested vector that trick doesn't quite work because it messes up the nesting.

You can email me with my first name at the company site to talk more. There's also a chat room at https://chat.stackexchange.com/rooms/52405/the-apl-orchard which is good for asking questions.