http://www.mathworks.com/matlabcentral/answers/42283-index-non-empty-cells-in-cell-array

x = {1,[],[],[]}; find(~cellfun(@isempty,x)) 

When MATLAB starts, it looks for a pathdef.m file in its startup directory.

Start up folder (in the icon | Properties | Start in ) (e.g. D:\Sources\MATLAB) allows controlling different paths and other settings via startup.m file placed in the folder, e.g.:

disp('Welcome to physiology analysis...');
set_sources_path; % set additional paths dynamically, e.g. 
% p = genpath('D:\Sources\MATLAB'); addpath(p);
 
cd('F:\Data');
edit;
EditorMacro('Alt-Control-h', @createHeaderComment_dag);
 
dbstop if error