The DaysInYear( year ) command computes the number of days in the year year. The number of days is either 365 for an ordinary year or 366 in a leap year. There is also an exception for the year 1582, the year of calendar reform, which is missing 10 days.

Leap years prior to $1582$ occur every four years.  After $1582$, the modern leap year rules are used.

Leap years prior to the year 5 were observed inconsistently, and may be historically incorrect.

$\mathrm{with}\left(\mathrm{Calendar}\right)\:$

$\mathrm{DaysInYear}\left(2000\right)$

$366$

$\mathrm{DaysInYear}\left(1100\right)$

$366$

$\mathrm{DaysInYear}\left(2100\right)$

$365$

$\mathrm{DaysInYear}\left(2001\right)$

$365$

$\mathrm{DaysInYear}\left(1900\right)$

$365$

$\mathrm{DaysInYear}\left(1995\right)$

$365$

$\mathrm{DaysInYear}\left(1582\right)$

$355$

$\mathrm{DaysInYear}\left(0\right)$

$366$

$\mathrm{DaysInYear}\left(4\right)$

$366$

The Calendar[DaysInYear] command was introduced in Maple 2018.

For more information on Maple 2018 changes, see Updates in Maple 2018.