function input arguments error

not sure how to solve this issue with function arguments,

I'm trying to do this to figure out how to return a vector y that contains both solutions: a logical variable isreal indicating whether the results were real (isreal=1) or imaginary (isreal=0). not sure if it would be the right approach.

Any help will be appreciated, thank you

myquad

Not enough input arguments.

Error in myquad (line 3)

D = b^2 - 4*a*c;

^

function [y, isreal] = myquad(a, b, c)
    % Calculate the discriminant
    D = b^2 - 4*a*c;

    % Calculate the two solutions using the quadratic formula
    y(1) = (-b + sqrt(D)) / (2*a);
    y(2) = (-b - sqrt(D)) / (2*a);

    % Check if the solutions are real
    isreal = all(isreal(y));

    % If the discriminant is negative, the solutions are complex
    if D < 0
        y = [NaN, NaN]; % Return NaN for complex solutions
        isreal = 0;     % Set isreal to false
    end
end

%In the command window I'm trying to call the function like this;

y = myquad(1, -2, 1);
disp(y);        % Output: [1, 1]
disp(isreal);   % Output: 1

[VBBV]

Please check the version of Matlab you are using . In some older version, the function defintions are not allowed before actually calling the function in the script file.

Answer 1

[Torsten]

Don't use isreal as a variable name: isreal is a MATLAB function that you overwrite this way.

[y, is_real] = myquad(1, -2, 1);
disp(y);        % Output: [1, 1]

     1     1

disp(is_real);   % Output: 1

   1

function [y, is_real] = myquad(a, b, c)
    D = b^2 - 4*a*c;    
    if D >=0
       is_real = true;
       y = [(-b + sqrt(D)) / (2*a),(-b - sqrt(D)) / (2*a)];
    else
      is_real = false;
      y = [NaN, NaN];
    end
end

[Cesar Cardenas]

Thank you, still getting the same error, sorry, not so good at matlab, can you show how to call the function?

[Matt J]

@Cesar Cardenas Torsten and I have both run our code for you so you can see how the function is called and that they produce the proper output. Please run your code for us online, so that we can all see it in action.

[Cesar Cardenas]

function [y, is_real] = myquad(a, b, c)
    D = b^2 - 4*a*c;    
    if D >=0
       is_real = true;
       y = [(-b + sqrt(D)) / (2*a),(-b - sqrt(D)) / (2*a)];
    else
      is_real = false;
      y = [NaN, NaN];
    end
end






[y, is_real] = myquad(1, -2, 1);
disp(y);        % Output: [1, 1]
disp(is_real);   % Output: 1

[Cesar Cardenas]

I found my mistake, it works now, thank you

Answer 2

[Matt J]

Your code uses 'isreal' as both the name of a function and a variable. You can resolve the conflict by renaming the output, e.g.,

[y,isReal] = myquad(1, -2, 1)

y = 1×2

1 1

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isReal = logical
   1

function [y, isReal] = myquad(a, b, c)

    % Calculate the discriminant
    D = sqrt(b^2 - 4*a*c);

    isReal=isreal(D);
    
    if ~isReal, y=nan(1,2); return; end
    
    % Calculate the two solutions using the quadratic formula   
    y = (-b + [-1,1]*D) / (2*a);

end