src/ExpressiveDate.php
public function setWeekStartDay($weekStartDay)
	{
		if (is_numeric($weekStartDay))
		{
			$this->weekStartDay = $weekStartDay;
		}
		else
		{
			$this->weekStartDay = array_search(strtolower($weekStartDay), array('sunday', 'monday'));
		}

		return $this;
	}
public function setWeekStartDay($weekStartDay)
	{
		if (is_numeric($weekStartDay))
		{
			$this->weekStartDay = $weekStartDay;
		}
		else
		{
			$this->weekStartDay = array_search(strtolower($weekStartDay), array('sunday', 'monday'));
		}

		return $this;
	}
public function setWeekStartDay ( $ weekStartDay ) { if ( is_numeric ( $ weekStartDay ) ) { $ this -> weekStartDay = $ weekStartDay ; } else { $ this -> weekStartDay = array_search ( strtolower ( $ weekStartDay ) , array ( 'sunday' , 'monday' ) ) ; } return $ this ; }
Set the starting day of the week, where 0 is Sunday and 1 is Monday.

@param int|string $weekStartDay
@return void
Set the starting day of the week where 0 is Sunday and 1 is Monday .