There are also a couple of modules out there on CPAN for this, for example Time::JulianDay. You could use it like this (which should also handle leap years correctly): 

use Time::JulianDay;

sub conv2jul {
    my ($moda, $year) = @_;
    my ($mon, $day) = unpack "A2A2", $moda;
    return julian_day($year, $mon, $day) - julian_day($year, 1, 0);
}

for my $year qw(2000 2007) {
    print "$year:\n";
    for my $moda qw(0112 0402 1231) {
        my $jd = conv2jul($moda, $year);
        printf "  %s --> %03s\n", $moda, $jd;
    }
}

[download]

would print: 

2000:          (leap year)
  0112 --> 012
  0402 --> 093
  1231 --> 366
2007:
  0112 --> 012
  0402 --> 092
  1231 --> 365

[download]

In reply to Re: Very Simple Conversion of Gregorian to Julian Calendar by almut
in thread Very Simple Conversion of Gregorian to Julian Calendar by Aim9b

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