a←(⎕a,⎕d)[?1e4 12⍴36]
g←a∘{(↓⍺)⍳↓⍵}
b ←a[?5000⍴1↑⍴a;]
(g b)≡a matiota b
1
cmpx 'g b' 'a matiota b'
g b → 1.55E¯3 | 0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
a matiota b → 2.93E¯3 | +88% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
b1←a[?10⍴1↑⍴a;]
(g b1)≡a matiota b1
1
cmpx 'g b1' 'a matiota b1'
g b1 → 0.00E0 | 0%
a matiota b1 → 1.40E¯3 | +287400% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
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