Set default values for Matlab function arguments

SetDefault.m

function SetDefault(argname,value)
%SETDEFAULT Provide a default value of VALUE for the argument ARGNAME.
%
%USAGE
%   SetDefault('x',1)
%   If no variable 'x' exists in the calling function, or if the variable exists
%   but it is empty, then this call assigns the value 1 to 'x'. If the variable
%   'x' already exists, and is non-empty, then no action is taken.
%

% Author: Chris Taylor
% Created: 20/02/2012

    existstr = ['~exist(''' argname ''')'];
    emptystr = ['isempty(' argname ')'];

    if evalin('caller',existstr) || evalin('caller',emptystr)
        assignin('caller',argname,value)
    end

end