Sorting & Searching: ⎕ct←0 Index   <<   >>

 
   i0←{⎕ct←0 ⋄ ⍺⍳⍵}

   x←(2*¯24)ׯ1e9+?1e6⍴2e9

   cmpx 'x⍳x' 'x i0 x'
  x⍳x    → 4.03E¯1 |   0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  x i0 x → 1.76E¯1 | -57% ⎕⎕⎕⎕⎕⎕⎕⎕⎕