TF = ismember (A, B) returns a logical array TF of the same size as A containing true for each corresponding element of A that is in B and false otherwise. Either input may instead be a date/time character vector, string array, or cell array of character vectors, which is promoted to a datetime array before the test. Membership is decided on the absolute instant, so two zoned inputs may be in different time zones. Similarly to NaN values, Not-A-Time (NaT) elements are not equal with each other and always return false.

TF = ismember (A, B, 'rows') only applies to datetime matrices with the same number of columns, in which case the logical vector TF contains true for each row of A that is also a row in B. TF has the same number of rows as A.

[TF, index] = ismember (A, B) also returns an index array of the same size as A containing the lowest index in B for each element of A that is a member of B and 0 otherwise. If the 'rows' optional argument is used, then the returning index is a column vector with the same rows as A and it contains the lowest index in B for each row of A that is a member of B and 0 otherwise.

Source Code: datetime