4.初等酉阵( Householder变换) H(u)=E(u,u;2)=E-2un,(u"=1) (1)H(u)=H(u)=H(u)1 (2)H(u)(a+ru)=a-ru,va∈u,r∈C(镜象变换) 返回返回 2 2 1 H H H ( u )  E( u,u; )  E  uu ,( u u  ) 4.初等酉阵(Householder变换) 1 (1) H H( u ) H( u ) H( u )    (2) H ( u )( a ru ) a ru , a u ,r C ( )        镜 象 变 换