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内容简介作者简介 - 科学与工程计算系

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T_full =<br />

0.2200<br />

T_part =<br />

3.1300<br />

d =<br />

3.0140 + 0.2555i<br />

ans =<br />

3.0140 + 0.2555i<br />

vk1=V(:,k);<br />

vk1=vk1/norm(vk1);v=v/norm(v);<br />

V_err=acos(norm(vk1'*v))*180/pi<br />

D_err=abs(D(k,k)-d)/abs(d)<br />

V_err =<br />

1.2074e-006<br />

D_err =<br />

4.2324e-010<br />

4.3.2 特征值问题的条件数<br />

【例 4.3.2-1】矩阵的代数方程条件数和特征值条件数。<br />

B=eye(4,4);B(3,4)=1;B<br />

format short e,c_equ=cond(B),c_eig=condeig(B)<br />

B =<br />

1 0 0 0<br />

0 1 0 0<br />

0 0 1 1<br />

0 0 0 1<br />

c_equ =<br />

2.6180e+000<br />

Warning: Matrix is close to singular or badly scaled.<br />

Results may be inaccurate. RCOND = 1.110223e-016.<br />

> In D:\MATLAB6P1\toolbox\matlab\matfun\condeig.m at line 30<br />

c_eig =<br />

1.0000e+000<br />

1.0000e+000<br />

4.5036e+015<br />

4.5036e+015<br />

【例 4.3.2-2】对亏损矩阵进行 Jordan 分解。<br />

A=gallery(5)<br />

[VJ,DJ]=jordan(A);<br />

[V,D,c_eig]=condeig(A);c_equ=cond(A);<br />

DJ,D,c_eig,c_equ<br />

A =<br />

-9 11 -21 63 -252<br />

70 -69 141 -421 1684<br />

-575 575 -1149 3451 -13801<br />

3891 -3891 7782 -23345 93365<br />

1024 -1024 2048 -6144 24572<br />

DJ =<br />

0 1 0 0 0<br />

0 0 1 0 0<br />

0 0 0 1 0<br />

0 0 0 0 1<br />

0 0 0 0 0<br />

D =<br />

Columns 1 through 4<br />

-0.0408 0 0 0<br />

0 -0.0119 + 0.0386i 0 0<br />

4

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