The DayOfWeek( d ) command computes the day of the week of the Date object d.

The DayOfWeek( year, month, day ) command computes the day of the week for the day-th day of the month month (1..12) in the year year.

Weekdays are numbered from $1$ to $7$, with $1$ denoting "Sunday", $2$ denoting "Monday", and so on, through $7$ which denotes "Saturday".

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

$\mathrm{DayOfWeek}\left(\mathrm{Date}\left(\right)\right)$

$3$

$\mathrm{DayOfWeek}\left(2000\,1\,1\right)$

$7$

$\mathrm{DayOfWeek}\left(2000\,12\,31\right)$

$1$

$\mathrm{DayOfWeek}\left(\mathrm{Date}\left(1900\,12\,31\right)\right)$

$2$

$\mathrm{DayOfWeek}\left(\mathrm{Date}\left(1977\,5\,3\,'\mathrm{timezone}'=''Asia/Tehran''\right)\right)$

$3$

$\mathrm{DayOfWeek}\left(1066\,10\,14\right)$

$7$

$\mathrm{DayOfWeek}\left(1066\,12\,25\right)$

$2$

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

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