HE:(1)C=P(A+O)P=(c )nxn P=B Ci=+bin(i=1,2,…,n) Gerschgorin圆盘定理 14-a月p-(4+h)R(O)=R(B) 14-1-R(B)+|h图PSP (2)Gk(C)=z: -(k +bkksrk B)c sk A=2=…m=G1(O)={:z-(列2+h21) ≤R(B)cS(t=1,2,…,m)返回 证: 1 P P B  − = 1 (1) ( ) ( ) C P A P c  ij n n − = + =  ( 1,2, , ) ii i ii c b i n = + =  Gerschgorin圆盘定理 | | | ( ) | ( ) ( ) j ii j i ii i i    − = − +  = c b R C R B | | | | ( ) | |     i j j i i ii − = −  + R B b 1 || || P P −   (2) ( ) { :| ( ) | ( )} G C z z b R B k k kk k = − +    Sk i i i i 1 2 m     = = = ( ) { :| ( ) | t t t G C z z b i i i i = − +  ( 1,2, , )  = S t m i ( ) t  R B i