zeros(n)：返回n by n值为零的矩阵
zeros(m,n) or zeros([m n]):返回m by n值为零的矩阵
zeros(m,n,'single'):返回single（单精度）的m by n零矩阵，single可以为double等
matlab中解释如下：
% ZEROS(N) is an N-by-N matrix of zeros.
%
% ZEROS(M,N) or ZEROS([M,N]) is an M-by-N matrix of zeros.
%
% ZEROS(M,N,P,...) or ZEROS([M N P ...]) is an M-by-N-by-P-by-... array of
% zeros.
%
% ZEROS(SIZE(A)) is the same size as A and all zeros.
%
% ZEROS with no arguments is the scalar 0.
%
% ZEROS(M,N,...,CLASSNAME) or ZEROS([M,N,...],CLASSNAME) is an
% M-by-N-by-... array of zeros of class CLASSNAME.
%
% Note: The size inputs M, N, and P... should be nonnegative integers.
% Negative integers are treated as 0.
%
% Example:
% x = zeros(2,3,'int8');
%
% See also EYE, ONES.