x(k+1:n,k+1:n)=x(k+1:n)(k+1:n)-x(k+1:n,k)*x(k,k+1:n); 修改为： x(k+1:n,k+1:n)=x(k+1:n,k+1:n)-x(k+1:n,k)*x(k,k+1:n); 试试
