Multiple conditional statements with logic

I want to write a function called under_age that inputs whether a person is too young or not. It has multiple inputs of age and limit.

If the age is less than the limit than too_young = true and if age is greater than too_young = false. I also want to put in a case when the age is inputed

In which case, the age is of the limit of automatically set to 21.

At the moment the function works if the person is too_young = true. But I can't figure out why it doesn't work when too_young = false.

function [too_young] = under_age(age, limit) 
if (nargin == 2)
    age < limit
    too_young = true;
elseif (nargin == 2)
    age >= limit
    too_young = false;      
elseif (nargin == 1) || isempty(limit)
    age < 21
    too_young = true;
elseif (nargin == 1) || isempty(limit)
    age >= 21
    too_young = false;
end

[Image Analyst]

Apparently this is homework, because it's a duplicate of this question. I will label it as homework, like it should have been originally so that no one gave complete solutions.

Answer 1

[Image Analyst]

Try this:

too_young = under_age(22, 21)
too_young = under_age(11, 25)
too_young = under_age(33) 
too_young = under_age(18)

function too_young = under_age(age, limit)
fprintf('nargin = %d\n', nargin);
if (nargin == 2)
    too_young = age < limit; % Returns true or false.
else
    too_young = age < 21; % Returns true or false.
end
end

[Abhiram Ram]

can you explain.your code

[Image Analyst]

Alright, I've added comments. So many that there is now more comments than code. It should be even more self-explanatory now.

% Top part of m-file:
% Call the under_age() function with various values and number of input arguments.
% First call with two input arguments, each with a different limit.
too_young = under_age(22, 21)
too_young = under_age(11, 25)
% Now call with no second input argument.  The under_age() function will assume a limit of 21.
too_young = under_age(33) 
too_young = under_age(18)

% Bottom part of m-file, the function definition.
function too_young = under_age(age, limit)
% Print out how many input arguments the user called the function with.
fprintf('nargin = %d\n', nargin);
if (nargin == 2)
    % The function was called with 2 input arguments.
    % We need to see if the age (first argument) is below or above limit (the second argument).
    too_young = age < limit; % Returns true or false.
else
    % The function was called with only one argument.  
    % So we need to check only this one age against a value of 21, not against any other value.
    too_young = age < 21; % Returns true or false.
end
end % Final end is required if the function is in the same m-file as the script, but not if it's all by itself in it's own m-file.

Answer 2

[Alberto Chavez]

I think you have part of your expressions in the statements section.

Maybe this works.

function [too_young] = under_age(age, limit) 
if (nargin == 2) && age < limit
    too_young = true;
elseif (nargin == 2) && age >= limit
    too_young = false;      
elseif (nargin == 1) && isempty(limit) && age < 21
    too_young = true;
elseif (nargin == 1) && isempty(limit) && age >= 21
    too_young = false;
end

[Thomas Sun]

This works for when there is two inputs but doesn't work for when there is only one input (e.g. when no 'limit' is inputted).

[Image Analyst]

You don't need all that complicated stuff. Did you try my code? It works fine, either for one or two inputs.

[Alberto Chavez]

Oh my bad, this should work.

function [too_young] = under_age(age,limit) 
if nargin==2
    if isempty(limit)==1
        if age<21
            too_young = true;
        elseif age>=21
            too_young = false;
        end
    elseif isempty(limit)==0
        if age<limit
            too_young = true;
        elseif age>=limit
            too_young = false;
        end
    end
elseif nargin==1
    if age<21
        too_young = true;
    elseif age>=21
        too_young = false;
    end
end

I had to restructure your code, you have 3 levels of possibilities in your inputs. First whether you have:

under_age(age,limit)
%% or
under_age(age)

%% Second, whether you have
limit=[] % or
limit=anynumber

%% Third, whether you have
age<limit || 21 % or
age>=limit || 21

I ran it on my PC and it works now.