无阻尼二自由系统固有频率的程序

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% 无阻尼二自由系统固有频率的程序 20180401A
: m$ A# m; J, ^/ P/ em1=100;m2=100;k1=200;k2=400;%
c1=0;c2=0;
) m; a  T# H$ A! `; q/ {x0=[1;0];xd0=[0;0];tf=50;dt=0.1;
M=[m1,0;0,m2];k=[k1+k2,-k2;-k2,k2];
& v/ S& K3 ~; M; \( B- rc=[c1+c2,-c2;-c2,c2];
8 @# b1 k! |# w! j! wA=[zeros(2,2),eye(2);-M\k,-M\c];
( F0 `$ z9 s+ A4 m6 Fy0=[x0;xd0];
$ V1 \' Y" x8 @4 M( ]5 i1 }  kfor i=1:round(tf/dt)+1
# _6 l# b1 u) V9 D9 i0 t    t(i)=dt*(i-1)
5 _6 |8 N) [, r" O. N    y(:,i)=expm(A*t(i))*y0;
% A/ o! g  n( a- Q# y: Q7 s. p) gend
subplot(2,1,1),plot(t,y(1,),grid  
subplot(2,1,2),plot(t,y(2,),grid
[p,lamda]=eig(A)

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# E- f, q3 H3 N$ N4 P0 wlamda =
  Columns 1 through 2
" u) c5 v/ I% z2 l1 F  0.000000000000000 + 3.020447918044219i  0.000000000000000 + 0.000000000000000i
" T9 h( [# @2 I7 d  0.000000000000000 + 0.000000000000000i  0.000000000000000 - 3.020447918044219i
9 G  H' i% |$ c# X  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
8 F8 i& e9 O" G0 r( W  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
; H& g6 h) Y/ V; D+ E9 K7 e  Columns 3 through 4
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
5 l7 s" b/ ?+ M  I. b  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
  h+ |8 s4 e/ C -0.000000000000000 + 0.936426384924271i  0.000000000000000 + 0.000000000000000i
  K- q$ t- E- T5 i5 E5 S  0.000000000000000 + 0.000000000000000i -0.000000000000000 - 0.936426384924271i

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鸿鹄重工

代码中有个笑脸是啥意思，此处应该是什么代码？