Not enough input arguments

im running below code in matlab online for my machine learning in coursera, can any one pls help for this error

function J = computeCostMulti(X, y, theta)
%COMPUTECOSTMULTI Compute cost for linear regression with multiple variables
%   J = COMPUTECOSTMULTI(X, y, theta) computes the cost of using theta as the
%   parameter for linear regression to fit the data points in X and y

% Initialize some useful values
m = length(y); % number of training examples

% You need to return the following variables correctly 
J = 0;

% ====================== YOUR CODE HERE ======================
% Instructions: Compute the cost of a particular choice of theta
%               You should set J to the cost.


J = (1/(2*m))*sum(((X*theta) - y).^2)


% =========================================================================

end

in command window the error is:

Not enough input arguments.

Error in computeCostMulti (line 7)

m = length(y); % number of training examples

Answer 1

[madhan ravi]

Type the below in command window:

 X = 1;
 y = 2;
 theta = 3;
 J = computeCostMulti(X, y, theta) 
 doc function % please read it