!! Submission failed: unexpected error: Error using computeCost Too many output arguments.

When I put this expression in MATlab I get:

!! Submission failed: unexpected error: Error using computeCost

Too many output arguments.

!! Please try again later.

function J = computeCost(X, y, theta)
data = load('ex1data1.txt');
m = 97;
X = [ones(m, 1), data(:,1)]; 
theta = zeros(2, 1); 
h = X * theta; 
y = data(:, 2); 
error = h - y; 
error_sqr = error.^2; 
q = sum(error_sqr); 
J = (1/ (2*m) * q)

[Walter Roberson]

Why are you overwriting the input X and y and theta?

What is the point of setting theta to 0 and then multiplying by theta ?

How can you be certain that data will always have exactly 97 rows?

[Martin Felipe Wohlgemuth Pinzon]

Thank you for your questions.

It is my first promgramming excercise.

Many things are wrong.

Please tell me where I overwrite the inputs X, y and theta.

There is no point on setting theta to 0. My mistake.

I have no certainty of the number of rows, I tried to have a definite result. Now I understand that my programming has to fit any data.

[Walter Roberson]

function J = computeCost(X, y, theta)

That line tells you that X, y, and theta are normally expected to be passed in as inputs.

data = load('ex1data1.txt');
m = 97;

Neither of those lines read or write X, y, or theta, so the input X, y, theta do not matter to those two lines.

X = [ones(m, 1), data(:,1)]; 
theta = zeros(2, 1); 
h = X * theta; 
y = data(:, 2); 

The first of those lines ignores any X that was passed in and overwrites X with values. The second discards theta that was passed in and overwrites theta with zeros. The fourth line discards y that was passed in and overwrites y with values.

Therefore no matter what was passed in for X, y, theta, the code will ignore them and do its own thing.