Returns the day of the week ()
mixed jddayofweek ( int julianday [, int mode] )

Returns the day of the week. Can return a string or an integer depending on the mode.

表 22. Calendar week modes

0 (Default) Returns the day number as an int (0=Sunday, 1=Monday, etc)
1 Returns string containing the day of week (English-Gregorian)
2 Returns a string containing the abbreviated day of week (English-Gregorian)