function input arguments error

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Cesar Cardenas
Cesar Cardenas 2025-8-29，0:54
编辑： VBBV 2025-8-29，7:28
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
  1 个评论
VBBV
VBBV 2025-8-29，7:27
编辑：VBBV 2025-8-29，7:28
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.

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采纳的回答

Torsten
Torsten 2025-8-29，1:05
编辑：Torsten 2025-8-29，1:25
Ran in:
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
  4 个评论
显示 2更早的评论
Cesar Cardenas
Cesar Cardenas 2025-8-29，2:03
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
Cesar Cardenas 2025-8-29，2:04
I found my mistake, it works now, thank you

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更多回答（1 个）

Matt J
Matt J 2025-8-29，1:04
编辑：Matt J 2025-8-29，1:30
Ran in:
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
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
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

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