key = keyHash (T) generates a uint64 scalar that represents the input array T. keyHash utilizes the 64-bit FNV-1a variant of the Fowler-Noll-Vo non-cryptographic hash function.

key = keyHash (T, base) also generates a 64-bit hash code using base as the offset basis for the FNV-1a hash algorithm. base must be a uint64 integer type scalar. Use this syntax to cascade keyHash on multiple objects for which a single hash code is required.

A datetime array is keyed on the instant its elements name and not on their wall clock and time zone, so the same moment expressed in two zones has the same hash code. An unzoned array, a zoned array and a leap-second array are three separate frames that never share a key, whatever instants they name, and the two instants sharing a wall clock across a daylight-saving fall-back stay distinct. The Format property is display only and is not part of the key. Two arrays that keyMatch reports as the same key always hash alike.

Note that unlike MATLAB, this implementation does not use any random seed. As a result, keyHash will always generate the exact same hash key for any particular input across different workers and Octave sessions.

Source Code: datetime