x←¯1e9+?1e6⍴2e9 f←x∘⍳ y←¯1e9+?1e4⍴2e9 (f y) ≡ x⍳y 1 cmpx 'f y' 'x⍳y' f y → 1.94E¯3 | 0% x⍳y → 1.42E¯1 | +7206% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕ y1←x[?10⍴⍴x] (f y1) ≡ x⍳y1 1 cmpx 'f y1' 'x⍳y1' f y1 → 0.00E0 | 0% x⍳y1 → 5.16E¯3 | +264000% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕