xlsxwriter.class.php
public static function xlsCell($row_number, $column_number, $absolute=false)
	{
		$n = $column_number;
		for($r = ""; $n >= 0; $n = intval($n / 26) - 1) {
			$r = chr($n%26 + 0x41) . $r;
		}
		if ($absolute) {
			return '$' . $r . '$' . ($row_number+1);			
		}
		return $r . ($row_number+1);
	}
public static function xlsCell($row_number, $column_number, $absolute=false)
	{
		$n = $column_number;
		for($r = ""; $n >= 0; $n = intval($n / 26) - 1) {
			$r = chr($n%26 + 0x41) . $r;
		}
		if ($absolute) {
			return '$' . $r . '$' . ($row_number+1);			
		}
		return $r . ($row_number+1);
	}
/*
@param $row_number int, zero based
@param $column_number int, zero based
@param $absolute bool
@return Cell label/coordinates, ex: A1, C3, AA42 (or if $absolute==true: $A$1, $C$3, $AA$42)