#!/usr/bin/perl -wl

use strict;
use Date::Calc 'Day_of_Week';


sub  day_of_week {

    my ($year, $month, $day) = @_;

    my @offset  = (0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4);
    $year      -= $month < 3;

    return ($year + int($year/4) - int($year/100) + int($year/400)
                  + $offset[$month-1] + $day) % 7;
}


my @days = (31,27,31,30,31,30,31,31,30,31,30,31);


for (1..1000) {

    my $year  = 1753 + int rand 4000;
    my $month = 1    + int rand 12;
    my $day   = 1    + int rand $days[$month-1];


    my @date = ($year,$month, $day);


    my $wd1 = day_of_week(@date);
    my $wd2 = Day_of_Week(@date);
    $wd2 = 0 if $wd2 == 7;

    print "@date:\t$wd1 != $wd2" if $wd1 != $wd2 ;

}
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--
John.