matlab输入参数数目不足

function S=sodoku(M,S)
%M=[0,0,1,9,0,0,0,0,8;6,0,0,0,8,5,0,3,0;0,0,7,0,6,0,1,0,0;...
% 0,3,4,0,9,0,0,0,0;0,0,0,5,0,4,0,0,0;0,0,0,0,1,0,4,2,0;...
% 0,0,5,0,7,0,9,0,0;0,1,0,8,4,0,0,0,7;7,0,0,0,0,9,2,0,0];
%
%S=sudoku(M)
if ~exist('S','var')
S=zeros([size(M),0]);
end
firstld=find(M(:)==0,1);
if isempty(firstld)
S(:,:,size(S,3)+1)=M;
else
[i,j]=ind2sub([9,9],firstld);
for k=1:9
ii=(ceil(i/3)-1)*3+1;
jj=(ceil(j/3)-1)*3+1;
mm=M(ii:ii+2,jj:jj+2);
if sum(M(i,:)==k)==0&&sum(M(:,j)==k)==0&&sum(mm(:)==k)==0
M(i,j)=k;
S=sodoku(M,S);
end
end
end
运行后显示输入参数的数目不足是什么原因呢