s = second (T) returns the number of seconds for each element of the input datetime array T. The output s is a double array containing values in the range $[1,\; 60)$, including any fractional part of the second, and it has the same size as T. Not-A-Time (NaT) values in T are returned as NaN in the output array.

s = second (T, secondType) returns the seconds for each element of the input datetime array T as specified by secondType, which may have any of the following options:

• 'secondofminute' (default) returns the second of the minute in a numeric array, in the range $[1,\; 60)$.
• 'secondofday' returns the second of the day in a numeric array, in the range $[1,\; 86400)$.

Source Code: datetime