my $dt = DateTime->now(time_zone => 'Local');

##</code><code>##

$day_of_year = $dt->doy;
$week_of_year = $dt->week_number;

##</code><code>##

$century = int($dt->year / 100)+1;
$millennium = int($dt->year / 1000)+1;

##</code><code>##

my $utc_dt = DateTime->now(time_zone => 'UTC');
$difference = $utc_dt - $dt;

##</code><code>##

$string = '2005-10-08T08:42';
$parser = DateTime::Format::ISO8601;

$parsed_dt = $parser->parse_datetime( $string );

$epoch_seconds = $parsed_dt->epoch;

##</code><code>##

$julian_day = $dt->jd;

$modified_julian_day = $dt->mjd;

##</code><code>##

$yesterdays_date = $dt->clone();
$yesterdays_date->subtract( days => 1 );