例如ones函数的源代码：看不太懂，求助！

Question

function [varargout] = ones(varargin)%ONES Ones array.% ONES(N) is an N-by-N matrix of ones.%% ONES(M,N) or ONES([M,N]) is an M-by-N matrix of ones.%% ONES(M,N,P,...) or ONES([M N P ...]) is an M-by-N-by-P-by-... array of% ones.%% ONES(SIZE(A)) is the same size as A and all ones.%% ONES with no arguments is the scalar 1.%% ONES(M,N,...,CLASSNAME) or ONES([M,N,...],CLASSNAME) is an M-by-N-by-...% array of ones of class CLASSNAME.%% Example:% x = ones(2,3,'int8');%% See also EYE, ZEROS.% Copyright 1984-2003 The MathWorks, Inc.% $Revision: 5.10.4.3 $ $Date: 2004/04/16 22:05:14 $% Built-in function.if nargout == 0builtin('ones', varargin{:});else[varargout{1:nargout}] = builtin('ones', varargin{:});end

Answer 1

if nargout == 0 % nargout代表函数实际输出参数的个数。
% 如果在命令行直接调用ones(...)，nargout=0
% 如果给一个变量赋值，比如a=ones(...)，nargout=1
% 如果给若干变量赋值，如[a, b, ...]=ones(...)，有几个变量，nargout就是几。
builtin('ones', varargin{:}); % 如果无输出参数，调用内建的ones函数
else
[varargout{1:nargout}] = builtin('ones', varargin{:}); % 否则，同样调用内建ones函数，但要给输出变量赋值返回的结果。varargout表示所有输出参数组成的队列。
end