Convert a Gregorian calendar date to Julian date number (JDN) in Perl faster, less overhead than using any Date packages from CPAN straight from the Wikipedia algorithm

julianify.pl

sub julianify {
	my ( $year, $month, $day ) = @_;
	my $a = int( ( 14 - $month ) / 12 );
	my $y = $year + 4800 - $a;
	my $m = $month + 12 * $a - 3;
	
	return
		  $day 
		+ int( ( 153 * $m + 2 ) / 5 ) 
		+ 365 * $y 
		+ int( $y / 4 )
		- int( $y / 100 ) 
		+ int( $y / 400 )
		- 32045;
}