Find

is a dyadic primitive function which tests if the left argument appears as a contiguous subarray of the right argument.

Examples
Both arguments can be arrays of any shape. The entire left argument is tested against each position in the right argument. The result is a boolean array having the same shape as the right argument, where a 1 indicates the position of the first element of the matched subarray (which can be seen as the "leftmost" or "top left" position in case of a vector or matrix). If the left argument has lower rank, it is treated as if the shape is prepended with ones. If the left argument has higher rank, Find does not error, but it is never found in the right argument (resulting in an all-zero array).

For nested arrays, Find tests for exact match between the elements.

Documentation

 * Dyalog
 * APLX
 * J Dictionary, NuVoc
 * BQN