function S=modeN_prod(S,A,n)
% @author:slandarer
% 模-n积

dimS=size(S);
dimA=size(A);

if dimA(2)~=dimS(n)
    error('Inner tensor dimensions must agree.');
end
% 张量维度排序及展开
N=ndims(S);
dimorder=1:N;
dimorder(dimorder==n)=[];
dimorder=[n,dimorder];
unfoldS=reshape(permute(S,dimorder),dimS(n),[]);
% 矩阵左乘
unfoldS=A*unfoldS;
% 张量大小计算及还原
dimS(n)=dimA(1);
S=ipermute(reshape(unfoldS,dimS(dimorder)),dimorder);
end