Time::Local (which should be in your Perl distribution) has a conversion mode where its date arguments aren't validated to be in the proper range. A nifty side-effect of this is that you can ask it to convert the 176th of January (or 10_000th second of 2003, or 1234th hour of February, etc), and it will Do What You Mean©. 
    use Time::Local 'timelocal_nocheck';

    my $year  = 2003 - 1900;
    my $dyear = 176;
    my $epoch = timelocal_nocheck 0,0,0,$dyear,0,$year;
                         ## January is month 0 ^

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Time::Local only converts Y/M/D,H:M:S to epoch seconds, but you can very easily extract out the month and day components from the epoch time with localtime: 
    my ($month, $day) = (localtime $epoch)[4,3];
    $month++;  ## again, months run from 0 to 11

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.. or you could format the date with whatever format you like, using strftime 
    use POSIX 'strftime';
    print strftime("%x", localtime $epoch), $/;

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For doing simple date calculations like this, using localtime and Time::Local is a lot less overhead than the behemoth Date::Calc.

UPDATE: If you only care about getting the text output (you don't need the day/month components individually), it looks like strftime also normalizes its input in the same way as timelocal_nocheck: 

$ perl -MPOSIX=strftime -le 'print strftime("%c", 0,0,0,176,0,103)'
Thu Jun 25 00:00:00 2003

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Also realized that I needed to use 2003-1900 (not just 2003) as the final argument to timelocal_nocheck, so updated that.

blokhead

In reply to Re: Need Help with DATE::CALC $doy by blokhead
in thread Need Help with DATE::CALC $doy by Anonymous Monk

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