Hints for Problem #5 - Exploding m-files

[MATLAB logo] Exploiting MATLAB's Data Structures

varargin and varargout are normal cell arrays that can be accessed and manipulated with the normal cell array syntax. That is, varargin{i} retrieves the i-th element, varargin{:} is a comma-separated list, etc.
varargout must show up as the last element in the output argument declaration of a function to be automatically mapped to the output arguments. It is ok to define more elements in varargout than nargout indicates were requested when the function was called. This is required when you want to always set ans when no outputs are requested. In this case set varargout{1} to your output value.
for loops are commonly required when dealing with cell arrays. The function explode isn't vectorizable.