⎕ct
1E¯14

   x← ×\ 1 , 10 ⍴ 1+⎕ct             y← ×\ 1, 1e6 ⍴ 1+⎕ct
   ⍴a ← ∪x                          ⍴b ← ∪y
1                                1  
   x ∊ a                            y ∊ b
1 1 0 0 0 0 0 0 0 0 0            1 1 0 0 0 0 0 0 0 0 0 ...

   14 ⍕ x
 1.00000000000000 1.00000000000001 1.00000000000002 
      1.00000000000003 1.00000000000004 1.00000000000005 
      1.00000000000006 1.00000000000007 1.00000000000008 
      1.00000000000009 1.00000000000010