I can't figure out why n=length(sigma) has gone wrong

function [V1,V2]=q3_test1(K,CD0,S,sigma,W,T0)
n = length(sigma);
V1=zeros(1,n);
V2=zeros(1,n);
for i = 1:n
    T = T0*sigma(i);
    rho = 1.225*sigma(i);
    if T^2 < 4*K*CD0*W^2
        V1 = -1;
        V2 = -1;
    else
        X1 = (T-sqrt(T^2-4*K*CD0*W^2))/2*CD0;
        V1 = sqrt(X1/(0.5*rho*S));
        X2 = (T+sqrt(T^2-4*K*CD0*W^2))/2*CD0;
        V2 = sqrt(X2/(0.5*rho*S));        
    end
end

end

[Stephen23]

Please show us exactly how you are calling q3_test1

Answer 1

[David Jacob]

What is the error message? What is the value for n?

[Samuel Walker]

Not enough input arguments.

Error in q3_test1 (line 15)

n = length(sigma);

[David Jacob]

Have you run the function properly by defining sigma first and then calling the function with sigma as an input?

[Walter Roberson]

You cannot just run the code by pressing the green Run button.

Well, you can do that, but the result is the error message you see,

When you run a function, MATLAB will never look in the calling environment to see if a variable has been defined with the same name as a parameter that has not been passed in. So when you run the code by pressing the green Run button, MATLAB will not check the base workspace (or any other workspace) to see if it can find values for K, CD0, S, sigma, W, or T0 to use in the function.

There are some circumstances under which other variables might be looked for in the calling environment, but never for variables named in the list on the function statement.