Need help on this program

My code is working for all random inputs, except for valid_date(2002,2,28). Could somebody please suggest? Thank you

function valid = valid_date(year,month,day)
if ((isscalar(year) && year>0 ) && (isscalar(month) && month>0) && (isscalar(day) && day>0))
%For Leap year
  if (((rem(year,4) == 0) && (rem(year,100) == 0) && (rem(year,400) == 0)) || ((rem(year,4) == 0) && (rem(year,100) ~= 0)))
       valid_leap = true;
  else
       valid_leap = false;
  end

% check for february 
    if(valid_leap == true && month==2 && day <=29)
       valid = true;
    else if(valid_leap == false && month==2 && day <=28)
       valid = true;
    else
       valid = false;
    end

% check for other months
    if (month==1 || month==3 || month==5 || month==7 || month==8 || month ==10 || month==12) && (day <= 31)
        valid = true;
    elseif (month==4 || month==6 || month==9 || month==11) && (day <= 30)
        valid = true;
    else
        valid = false;
    end
    end
else 
    valid = false;
end

Answer 1

[Meg Noah]

Try something like this:

function valid = valid_date(year,month,day)
if ((isscalar(year) && year>0 ) && (isscalar(month) && month>0) && (isscalar(day) && day>0))
    %For Leap year
    if (((rem(year,4) == 0) && (rem(year,100) == 0) && (rem(year,400) == 0)) || ((rem(year,4) == 0) && (rem(year,100) ~= 0)))
        valid_leap = true;
    else
        valid_leap = false;
    end
    
    % check for other months
    if ismember(month,[1 3 5 7 8 10 12]) && (day <=31)
        valid = true;
    elseif ismember(month,[4 6 9 11]) && (day <= 30)
        valid = true;
    elseif (month == 2 && valid_leap == true && day <=29)
        valid = true;
    elseif (month == 2 && valid_leap == false && day <=28)
        valid = true;
    else 
        valid = false;
    end

end

[Sri Thota]

Hey Meg Noah, Thanks so much for the help : ) It worked.