Error in Function writing

Trying to create a function of the logistic map xn+1=mu*xn*(1-xn) to calculate and output N+1 states, but I keep getting the error 'Undefined function or variable 'mu'' after using mu as an input argument to the function. Anyone know how to fix this?

function output= logistic_map(mu,x0)
    N=20;   % the number of states to be generated after the initial state
    % Error check
    if mu > 4 || mu < 0
        error('mu parameter must lie in the range 0 to 4 ')
        return  % forcing an early return
    end
    
    x=x0;
    output= zeros(1, N+1); % Storage matrix of N+1 numbers
    output(1,1)=x; % The first value in the matrix is initialised to the first value of x
    
    for count = 1:N
        x=mu*x*(1-x);
        output(1,count+1)=x;
    end
    end

Answer 1

[Jan]

How do you call this function? Do you start it by pressing the "Run" button? This does not define the inputs.

Call this function from the command windows or from another script or function with defining the input arguments, e.g.:

output= logistic_map(2, 3)