Write a model of ⍸x .
where←{...} where 1 0 1 0 0 1 0 0 1 3 6 where 3 4⍴1 0 1 0 0 ┌───┬───┬───┬───┬───┐ │1 1│1 3│2 2│2 4│3 3│ └───┴───┴───┴───┴───┘ where 1 2 3 DOMAIN ERROR where←{(,~~⍵)/,⍳⍴⍵}