Gradient Descent - fix

Hi all,

I have the following code for one of the assignments on Gradient Descent for Machine Learning, Coursera:

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
data = load('ex1data1.txt'); % read comma separated data
y = data(:, 2);
m = length(y); % number of training examples
X = [ones(m, 1), data(:,1)]; % Add a column of ones to x
theta = zeros(2, 1);
m = length(y); % number of training examples
J_history = zeros(num_iters, 1);
delta = zeros(2, 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.
    %

for i = 1:m
        Xi = X(i,:);
        hi = Xi*theta;
        delta = delta + (hi-y(i))*(Xi');
    end
    delta = delta/m;
    theta = theta - alpha*delta;
    delta = 0;
    % ============================================================

    % Save the cost J in every iteration    
    J_history(iter) = computeCost(X, y, theta);

end

end

It gives me the following error code:

>> gradientDescent()
Not enough input arguments.

Error in gradientDescent (line 13)
J_history = zeros(num_iters, 1);

I cannot find an answer to this. Any idea how to fix it?

Answer 1

[Matt J]

Call your function with all 5 input arguments.

[Nektarios Liaskos]

Could you kindly elaborate on this?

I am fairly new to this and struggle to apply what you are recommending.

As far as I can tell num_inter has not been defined (the error lies in the pre-written code that was given with the assignment and is not part of the code I have to write for this task, which is why I am sruggling so much).

Thank you! :)

[Matt J]

num_iters is the fifth input argument to your function.

[theta, J_history] = gradientDescent(X, y, theta, alpha, num_iters)

It is therefore your job to provide this value as input when you call the function.

[Nektarios Liaskos]

Oh of course, I sorted it now using the accessory files. Thank you!

[Matt J]

You're quite welcome, but please Accept-click the answer to indicated that the question has been resolved.

[Samuel Valentin Lopez Valenzuela]

i have the same problem , how did you use accessory files to fix it?

[Aniket Anand]

Can you please help me out

I don't know how to use accessory files