nargin, nargout (MATLAB Function Reference)

Number of function arguments

n = nargin
n = nargin('fun')
n = nargout
n = 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 M-file function fun or -1 if the function has a variable of input arguments.

nargout

returns the number of output arguments specified for a function.

nargout('fun')

returns the number of declared outputs for the M-file function fun.

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