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
  Q, `, D) Q' s8 f/ Z* em1=100;m2=100;k1=200;k2=400;%
, n" N( _: ]( n' y& Nc1=0;c2=0;
x0=[1;0];xd0=[0;0];tf=50;dt=0.1;
+ c1 E( @0 b% ~2 Z. K3 s" i3 o. e% `M=[m1,0;0,m2];k=[k1+k2,-k2;-k2,k2];
/ ^, z% z( p$ z1 o) \7 qc=[c1+c2,-c2;-c2,c2];
* g9 Z# a% U: }& H. P, }A=[zeros(2,2),eye(2);-M\k,-M\c];
y0=[x0;xd0];
for i=1:round(tf/dt)+1
    t(i)=dt*(i-1)
    y(:,i)=expm(A*t(i))*y0;
end
8 e; c- b2 `$ dsubplot(2,1,1),plot(t,y(1,),grid  
% u4 `0 ^% Y+ msubplot(2,1,2),plot(t,y(2,),grid
. z7 U) F" t0 B5 P5 Z# l- h[p,lamda]=eig(A)
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- A* Q1 w1 y% Y) W. x  Y; K
lamda =
  Columns 1 through 2
9 S: {# T) L9 \) A( d  0.000000000000000 + 3.020447918044219i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i  0.000000000000000 - 3.020447918044219i
+ S3 j8 B  V0 O5 a  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
7 F0 _$ D' D5 e+ m: ?% O$ e8 s( ^0 Z  Columns 3 through 4
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
7 c% g: V% s/ t$ S -0.000000000000000 + 0.936426384924271i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i -0.000000000000000 - 0.936426384924271i
9 _5 T% |& Y) K% y5 L

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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？