Find
From NARS2000


L and R are arbitrary arrays of any rank, shape, or datatype.
But to be useful,


Z is a Boolean array of the same rank and shape as R where each 1 represents the upper left corner of a place in R of a match with L. 
If L is a scalar, then L⍷R ←→ R∊L.
If L is not a scalar, then it represents a contiguous pattern, which may or may not be found in one or more places in R.
If the arguments are numeric, then the result is sensitive to ⎕CT.
For example:
R←3 8⍴'thirteenfourteenfifteen ' R thirteen fourteen fifteen 't'⍷R 1 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 'teen'⍷R 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 (2 4⍴'teen')⍷R 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0