Y may be any array. X may be any array. R is Boolean. An element of R is 1 if the corresponding element of X can be found in Y.
An element of X is considered identical to an element in Y if X≡Y returns 1 for those elements.
⎕CT and ⎕DCT are implicit arguments of Membership.
'THIS NOUN' ∊ 'THAT WORD' 1 1 0 0 1 0 1 0 0 'CAT' 'DOG' 'MOUSE' ∊ 'CAT' 'FOX' 'DOG' 'LLAMA' 1 1 0
For performance information, see Search Functions and Hash Tables.