The output of datenum are whole days to the left of the decimal separator (as the number of days from January 0, 0000), and fractions of a day to the right. You can get other details about the days using the appropriate datetime (link) functions.
Example —
dn = now % Date Number
dt = datetime(dn, 'ConvertFrom','datenum') % Corresponding ‘datetime’ Object
daynr = day(dt) % Day Of The Month
dayyr = day(dt, 'dayofyear') % Day Of The Year
dn =
737187.560337454
dt =
07-May-2018 13:26:53
daynr =
7
dayyr =
127
