varargin, varargout in matlab

varargin, varargout

Return variable number of arguments

Syntax

• function varargout = foo(n)
  function y = bar(varargin)
  

Description

function varargout = foo(n) returns a variable number of arguments from function foo.m.

function y = bar(varargin) accepts a variable number of arguments into function bar.m.

The varargin and varargout statements are used only inside a function M-file to contain the optional arguments to the function. Each must be declared as the last argument to a function, collecting all the inputs or outputs from that point onwards. In the declaration, varargin and varargout must be lowercase.

Examples

The function

• function myplot(x,varargin)
  plot(x,varargin{:})
  

collects all the inputs starting with the second input into the variable varargin. myplot uses the comma-separated list syntax varargin{:} to pass the optional parameters to plot. The call

• myplot(sin(0:.1:1),'color',[.5 .7 .3],'linestyle',':')
  

results in varargin being a 1-by-4 cell array containing the values 'color', [.5 .7 .3], 'linestyle', and ':'.

The function

• function [s,varargout] = mysize(x)
  nout = max(nargout,1)-1;
  s = size(x);
  for k=1:nout, varargout(k) = {s(k)}; end
  

returns the size vector and, optionally, individual sizes. So

• [s,rows,cols] = mysize(rand(4,5));
  

returns s = [4 5], rows = 4, cols = 5.