use Date::Manip;

$date1 = ParseDate("20071001");
$date2 = ParseDate("20070926");
print DateCalc($date1,"- 3 business days"),"\n";
print DateCalc($date1,$date2,\$err),"\n"; # regular mode... 5 days
print DateCalc($date1,$date2,\$err,2),"\n"; #business mode... 3 days