It depends how you want to handle it. Do you want 'b' to be an optional argument or do you want to force the caller to always give a value for b and support [] as a a value for it?
As the final argument to a function there is not usually much point doing the latter so I would just do e.g.
function out = myFunction( a, b )
narginchk( 1, 2 )
if exist( 'b', 'var' )
% Do some validation - optional I suppose!!
else
b = 0.1;
end
If you wanted to support 'a' being optional then you could do this by allowing [] to be a valid input and would do like above, but include
if exist( 'a', 'var' ) && ~isempty( a )
