You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ackley.m
    path of file: ./repos/optimviz
    
    the code of the file until where you have to start completion: function varargout = ackley(x)
%ACKLEY Ackley's function

    
function varargout = ackley(x)
%ACKLEY Ackley's function

if nargin == 0
    varargout{1} = [-8,-8];     % LB
    varargout{2} = [2,2];       % UB
    varargout{3} = [0,20];      % Zlim
    varargout{4} = [-26.5,60];  % view
    varargout{5} = [0,0];       % xmin
    varargout{6} = 'Ackley function';    % name
    varargout{7} = [-6,-5];     % default x0    
    return;
end