why I get error in scalar portion?

function valid = valid_date(year, month, day)
if nargin <3 && nargin > 3 && year < 1 && month < 1  && month > 13 && ~(isscalar(year) && isscalar(month) && isscalar(day)) 
    valid = false; 
else
    if  (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) && day < 32 && day > 0
        valid = true;
    elseif (month == 4 || month == 6 || month == 9 || month == 11 ) && day < 31 && day > 0
        valid = true;
    elseif month == 2 && day < 29 && day > 0
        valid = true;
    elseif ((mod(year,4) == 0 && ~mod(year, 100) == 0) ||  (mod(year,4) == 0 && mod(year, 400) == 0)) && month == 2 && day == 29
        valid = true;
    else
        valid = false;
    end
end
end

[Steven Lord]

Please show how you're calling valid_date and the full and exact text of the error message you receive (all the text displayed in red in the Command Window.)

In addition please pass along to your professor my suggestion to choose a different problem to assign as homework in the future, as this question has been asked about and discussed on MATLAB Answers a few (hundred) times before.

[the cyclist]

I don't know if it is the source of your error, but you might want to double-check this part of your code ...

if nargin <3 && nargin > 3 ...

Answer 1

[Prateek Rai]

Hi,

You should first check for the scalar portion and then for other conditions.

Additionaly, you should also check for:

if nargin <3 && nargin > 3 && year < 1 && month < 1  && month > 13

It will only be true when all the conditions satisfy at the same time. It should be something like:

if nargin <3 || nargin > 3 || year < 1 || month < 1  || month > 13    

So the whole code would be:

function valid = valid_date1(year, month, day)
if ~(isscalar(year) && isscalar(month) && isscalar(day)) || nargin <3 || nargin > 3 || year < 1 || month < 1  || month > 13 
    valid = false; 
else
    if  (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) && day < 32 && day > 0
        valid = true;
    elseif (month == 4 || month == 6 || month == 9 || month == 11 ) && day < 31 && day > 0
        valid = true;
    elseif month == 2 && day < 29 && day > 0
        valid = true;
    elseif ((mod(year,4) == 0 && ~mod(year, 100) == 0) ||  (mod(year,4) == 0 && mod(year, 400) == 0)) && month == 2 && day == 29
        valid = true;
    else
        valid = false;
    end
end
end