When you call the method like:
[a,b,c,d] = obj.get_File(pathname,filename);
you're calling it with THREE input arguments, not two. As stated in the documentation, these two commands are equivalent in most circumstances.
[a,b,c,d] = obj.get_File(pathname,filename);
[a,b,c,d] = get_File(obj,pathname,filename);
They even have the same number of characters, though the first has a period and the second a comma.
So either define your function differently:
function [x,y,z,w] = get_File(obj,pathname,filename)
or, if get_File doesn't actually use the object (the section you quoted doesn't, though perhaps part of the code you snipped out does) make it a static method or perhaps a plain old function.
