disp('this program calculates the day of year given the');
disp('current date.');
month=input('Enter current month (1-12):');
day=input('Enter current day (1-31):');
year=input('Enter current year (yyyy):');

if mod(year,400)==0;
    leap_day=1;
    
elseif mod(year,100)==0;
leap_day=0;

elseif mod(year,4)==0;
leap_day=1;

else
 leap_day=0;
end
day_of_year=day;

for ii=1:month-1
    switch(ii)
   case{1,3,5,7,8,10,12},
            
 day_of_year=day_of_year+31;
 
  case{4,6,9,11}, 
      
      day_of_year=day_of_year+30;
      
        case 2,
            
      day_of_year=day_of_year+28+leap_day;
      
    end
end

      fprintf(' the date %2d/ %2d/ %4d is day of year %d.\n',month,day,year,day_of_year);\