n←1e6
   b←1=?n⍴2
   i←⍳n

13.1
      cmpx 'b/⍳⍴b' 'b/⍳n' 'b/(⍳n)' 'b/i'
  b/⍳⍴b  → 6.29E¯3 |   0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  b/⍳n   → 6.23E¯3 |  -1% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  b/(⍳n) → 4.76E¯3 | -25% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕     
  b/i    → 2.50E¯3 | -61% ⎕⎕⎕⎕⎕⎕⎕⎕            

13.2
      cmpx 'b/⍳⍴b' 'b/⍳n' 'b/(⍳n)' 'b/i'
  b/⍳⍴b  → 1.77E¯3 |    0% ⎕⎕⎕⎕⎕⎕⎕⎕            
  b/⍳n   → 1.77E¯3 |   -1% ⎕⎕⎕⎕⎕⎕⎕⎕            
  b/(⍳n) → 4.55E¯3 | +156% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  b/i    → 2.50E¯3 |  +41% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕