MATLAB: Noob problem: Defining a fumction and passing values issues an error “Subscript indices must either be real positive integers or logicals.”

function

I have the following function:
function [ result ] = SSD( i1, i2 )
if size(i1) == size(i2)
    [r, c] = size(i1)
    result = -(sum(sum((double(i1) - double(i2)).^2)) / (r*c));
else
    result = 'invalid';
end
I would like to pass it to images that contain gray values only and the error:
Subscript indices must either be real positive integers or logicals.
Popes up. For debugging purpuse I tried calling the function in this way:
SSD(zeros(3), ones(3));
The error is still there. But if I call the function in this way:
SSD(ones(3), ones(3));
No error. What is happening? Why doesn't the function like zero values?

Best Answer

Runs fine on my machine-no errors. 2015a. Do you have a variable named SSD or zeros?
Related Question