[SOLVED] there is an error message like "error: parse error near line" every time i try to run this code and i don't know what to do?

there is an error message like "error: parse error near line" every time i try to run this code and i don't know what to do?

function [theta, J_history] = gradientDescent(X, y, theta, alpha, num_iters)
%GRADIENTDESCENT Performs gradient descent to learn theta
%   theta = GRADIENTDESCENT(X, y, theta, alpha, num_iters) updates theta by 
%   taking num_iters gradient steps with learning rate alpha

% Initialize some useful values
m = length(y); % number of training examples
J_history = zeros(num_iters, 1);

for iter = 1:num_iters

    % ====================== YOUR CODE HERE ======================
    % Instructions: Perform a single gradient step on the parameter vector
    %               theta. 
    %
    % Hint: While debugging, it can be useful to print out the values
    %       of the cost function (computeCost) and gradient here.
    %
    %theta(iter)=theta(iter)-0.01*(1/m)*(((theta(1)+theta(2))*X-y)*X(iter,2))
    theta=theta-(alpha*(1/m)*(X*theta-y)*X(iter,2);
         % ============================================================
    % Save the cost J in every iteration    
    J_history(iter) = computeCost(X, y, theta);

end

end

Solution

theta=theta-(alpha*(1/m)*(X*theta-y)*X(iter,2);

The parentheses are not balanced as far as I can tell?

You're missing a closing parenthesis ) somewhere, are you not?