Index in position _ exceeds array bound when executing function, but not when running interactively

I wrote the following function:

function f = ll_func(theta)

global cover premium draws cost

% Extract input parameters
alpha = theta(1);
beta = theta(2);
mu = theta(3);
sigma = theta(4);
delta = theta(5);

% Demand probabilities
eu = beta*cover + alpha*premium + mu + sigma*draws; % Expected utility of each plan
num = exp(eu);
denom = sum(num, 5);
demprob = num./denom;

% Cost probabilities
meandraws = mean(draws(:,:,:,:,1:5), 1);
costprob = normpdf(cost - delta - sigma*meandraws);
costprob = costprob(1,:,:,:,:);

% Log-likelihood
demside = sum(log(mean(prod(prod(demprob.^choice, 5), 4), 2)), 'all');
supside = sum(log(mean(prod(costprob, 4), 2)), 'all');
f = -(demside + supside);
end

When I run

theta = [-1;1;1;2;3];
ll_func(theta);

I get the error

Index in position 5 exceeds array bounds (must not exceed 1).

Error in ll_func (line 19)
meandraws = mean(draws(:,:,:,:,1:5), 1);

but when I run the code in ll_func.m interactively it doesn't throw this error. What is going on here?

Answer 1

[Matt J]

What's going on is size(draws,5)=1. You have passed in data whose dimensions are not what the code expects. This may be connected with the fact that you are using global variables, which is usually unrecommended - if draws was changed somehow in the base workspace between runs by another function, it is harder to see.

[Alexander van Saase]

Yes I got that from the error, but it is not actually true though:

>> size(draws, 5)

ans =

     6

Running the contents from ll_func.m manually instead of calling the function doe not trows this errer either. ll_func. m is the only function in my script, so i think using global variables should be safe in this case. Attached are my full script and ll_func.m.

[Matt J]

We cannot run the code, because we do not have the .csv data files.

[Alexander van Saase]

My appolgies. Attached to this comment.

[Matt J]

When I pause execution at line 19 in ll_func,

I find that draws and the other global variables are empty:

K>> whos cover premium draws cost

  Name         Size            Bytes  Class     Attributes

  cost         0x0                 0  double    global    
  cover        0x0                 0  double    global    
  draws        0x0                 0  double    global    
  premium      0x0                 0  double    global    

This happens because they are not declared as global in the workspace of eio1ass2.m.