use DateTime;
use DateTime::Event::Sunrise;
use strict;

my $timezone = "Pacific/Auckland";
my ( $latitude, $longitude ) = ( -36.55, 174.45 );

my $dt_start = DateTime->new(
    year       => 2006,
    month      => 3,
    day        => 1,
    hour       => 4,
    time_zone  => $timezone,
);

my $dt_end = $dt_start->clone()->add(days=>31);

for ( my $dt = $dt_start->clone();
      $dt < $dt_end;
      $dt->add(days=>1)
     )
{
    my $sset = DateTime::Event::Sunrise->sunset(
        longitude => $longitude,
        latitude => $latitude,
        altitude => '-0.833',
        iteration => '1'
    );

    my $dt_ss = $sset->next($dt);

    print( "Sunset on "
           . $dt->strftime("%d %B %Y")
           . " at "
           . $dt_ss->strftime("%H:%M")
           . "\n"
          );
}

##</code><code>##

Sunset on 19 March 2006 at 18:38
Sunset on 20 March 2006 at 18:36
Sunset on 21 March 2006 at 18:33
Sun never sets!!
 at /usr/lib/perl5/vendor_perl/5.8.5/DateTime/Set.pm line 240
Sun never sets!!
 at /usr/lib/perl5/vendor_perl/5.8.5/DateTime/Set.pm line 240
Sun never rises!!
 at /usr/lib/perl5/vendor_perl/5.8.5/DateTime/Set.pm line 240
Sun never rises!!