argn Returns the number of input/output arguments in a function call [lhs [,rhs] ]=argn() lhs=argn(1) rhs=argn(2) This function is used inside a function definition. It gives the number of actual inputs arguments (rhs) and output arguments (lhs) passed to the function when the function is called. It is usually used in function definitions to deal with optional arguments. Note that lhs is always greater than or equal to 1. That is to say, even if a function is called without having mentioned an output argument, lhs will be equal to 1. function varargin