nargin-----输入参数个数判断------matlab

nargin, nargout

Number of function
arguments
Syntax

nargin
nargin(fun)
nargout
nargout(fun)
Description

In the body of a function M-file, nargin and nargout
indicate how many input or output arguments, respectively, a user has supplied.
Outside the body of a function M-file, nargin and nargout indicate the number of
input or output arguments, respectively, for a given function. The number of
arguments is negative if the function has a variable number of arguments.

nargin returns the number of input arguments specified for a
function.

nargin(fun) returns the number of declared inputs for the
function fun. If the function has a variable number of input arguments, nargin
returns a negative value. fun may be the name of a function, or the name of
Function Handles that map to specific functions.

nargout returns the number of output arguments specified for
a function.

nargout(fun) returns the number of declared outputs for the
function fun. fun may be the name of a function, or the name of Function Handles
that map to specific functions.
Examples

This example shows portions of the code for a function
called myplot, which accepts an optional number of input and output
arguments:

function [x0,
y0] = myplot(x, y, npts, angle, subdiv)
% MYPLOT Plot a
function.
% MYPLOT(x, y, npts, angle, subdiv)
% The first two input arguments are
% required; the other three have default values.
...
if nargin < 5, subdiv = 20; end
if nargin < 4, angle = 10; end
if nargin
< 3, npts = 25; end
...
if nargout
== 0
plot(x, y)
else
x0 = x;
y0 = y;
end