clear; close all
%
%  Calculate the day of year for a given date
%
days_in_mo = [31 28 31 30 31 30 31 31 30 31 30 31];
%
%  Get year, see if it's a leap year
%  If so, make it 29 days in Feb
%
done = 0;
while ~done
    year = input('Year: ');
    done = year > 0;
end
leap = 0;
if mod(year,400) == 0
    leap = 1;
elseif mod(year,100) == 0
    leap = 0;
elseif mod(year,4) == 0
    leap = 1;
end;
if leap
    days_in_mo(2) = 29;
end
%
%  Get month & day-of-month
%
done = 0;
while ~done
    month = input('Month number: ');
    done = month > 0 & month < 13;
end
done = 0;
while ~done
    day = input('Day of month: ');
    done = day > 0 & day <= days_in_mo(month);
end
%
%  Sum lengths of previous months added to given day
%
day_of_yr = sum(days_in_mo(1:month-1)) + day