To check Scalar or Not

I have debugged the code and now the Scalar test for this code is failing although I have given a provition in the 3rd line of the code to check wheather the given inputs are scalar or not.

please help!

function valid = valid_date(year,month,day)
if nargin==3
    if fix(month) && isscalar(month) && fix(day) && isscalar(day) && fix(year) && isscalar(year) && isscalar(valid_date) && year>0 && month>0 && day>0
        if mod(year,4)==0&&mod(year,100)~=0 || mod(year,400)==0&&mod(year,100)==0
            if ismember(month,[1,3,5,7,8,10,12]) && ismember(day,[1:31])
            valid=true;
            elseif month==2 && ismember(day,[1:29])
            valid=true;
            elseif ismember(month,[4,6,9,11]) && ismember(day,[1:30])
            valid=true;
            else
            valid=false;    
            end
        else
            if ismember(month,[1,3,5,7,8,10,12]) && ismember(day,[1:31])
            valid=true;
            elseif ismember(month,[4,6,9,11]) && ismember(day,[1:30])
            valid=true;
            elseif month==2 && ismember(day,[1:28])
            valid=true;
            else
            valid=false;
            end
        end
    else
    valid=false;
    end
else
valid=false;
end

Assessment result: correctVarious inputs
 Assessment result: incorrectNon-scalar
Return false if an input is not scalar...
 Assessment result: correctThe last day of every month
 Assessment result: correctRandom leap years
 Assessment result: correctRandom non-leap years
 Assessment result: correctRandom dates

[Stephen23]

What is this supposed to test for?:

isscalar(valid_date)

You recursively call the function (with no input arguments) and check if the function output is scalar. What is that supposed to detect?

Note that these square brackets are superfluous:

[1:31]
^    ^ not needed!

See: https://www.mathworks.com/matlabcentral/answers/35676-why-not-use-square-brackets

[Rakeshwar Elango]

Thank you stephen.

This is a test for cheking wheather a given date is valid or not without using inbuilt matlab functions for checking date. Except the Scalar test every other test like leap year or not etc, were detected properly.

I want to know what error is their in my code that prevents it from checking a date(scalar or not!)

Since other isscalar functions failed I tried isscalar for valid_date although it did not contain any arguments hoping it may solve!

[Akuroma George]

Hello Rakeshwar, were you able to finally figure this assignment out? If yes, what worked for you.

I am also stuck here and i don't know what else t0 do.

[Nisarg Dalal]

Hello Rakeshwar. I too am stuck at this same error.

If you were able to figure out the problem, let me know what you did

[Sunney Kumar]

      funtion valid = valid_date(year, month, day) 
       [i, j] = size(year);
       [k, l] = size(month);
       [o, p] = size(day);
    if (i == 1 && j ~= 1) || (k == 1 && l ~= 1) || (o == 1 &&  p ~= 1)
           valid = false
    else
        %rest of the code
    end
 

Try this piece of code to find out about whether input is scalar or not.

[Hakan Karapinar]

if (~isscalar(year) || year < 1 || year ~= fix(year) ) ||  (~isscalar(month) || month < 1 || month ~= fix(month) ) || (~isscalar(day) || day < 1 || day ~= fix(day) )
    valid = false
    return ;
    check my code out bro.we take same course.:D its worked i passed week 6

Answer 1

[Stephen23]

The reason is likely because of the order you check the inputs with, e.g.:

fix(month) && isscalar(month)
%^^^^^^^^^                    what is this supposed to test for?
%             ^^^^^^^^^^^^^^  this must be tested first!

If month is non-scalar, then fix(month) will return a non-scalar value, and then this will throw an error because && does not accept non-scalar input values. If you test isscalar first, then for a non-scalar month it will return false (i.e. a scalar!) and then MATLAB does not evaluate anything that follows the &&. Read the documentation to know more:

https://www.mathworks.com/help/matlab/ref/logicaloperatorsshortcircuit.html

Note that it is unclear what your fix(...) code is supposed to achieve, but I doubt that it does anything very useful. In any case, the order should be like this:

isscalar(month) && ??? you need to decide what to put here

Answer 2

[iitm_pnkj]

function valid = valid_date(year, month, day)
m31 = [1 3 5 7 8 10 12];
m30 = [4 6 9 11];

if isscalar(year) == 1 && isscalar(month) == 1 && isscalar(day) == 1 && year > 0 && month > 0 && day > 0
    if (mod(year,100) == 0 || mod(year,4) ~= 0) && month == 2 && day <=28
        valid = true;
    elseif ((mod(year,100) ~= 0 && mod(year,4) == 0) || (mod(year,400) == 0)) && month == 2 && day <= 29
        valid = true;
	elseif day <= 31 && any(m31(:)== month) == 1
        valid = true;
	elseif day <= 30 && any(m30(:)== month) == 1
        valid = true;
    else
        valid = false;
    end
else
    valid = false;
end
end

[Walter Roberson]

All those == 1 are unneeded. isscalar() already returns false or true.

The comparisons to 0 are valid, though.