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
m1=100;m2=100;k1=200;k2=400;%
3 o+ K3 Y: A- X; E5 Lc1=0;c2=0;
' A" |1 Q! e8 D% b5 ex0=[1;0];xd0=[0;0];tf=50;dt=0.1;
( {5 z) s/ M6 b1 Q t( R0 S- O. nM=[m1,0;0,m2];k=[k1+k2,-k2;-k2,k2];
c=[c1+c2,-c2;-c2,c2];
- A1 s$ @8 y: X+ X2 R5 a$ d; vA=[zeros(2,2),eye(2);-M\k,-M\c];
y0=[x0;xd0];
for i=1:round(tf/dt)+1
5 u* e5 _, T! O9 p* B6 }+ _- [t(i)=dt*(i-1)
# J4 {$ V4 e \5 k) k) C Cy(:,i)=expm(A*t(i))*y0;
- z0 [# |7 d* Pend
! Y5 ^9 b5 ~; n9 F6 ~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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# d6 [* Y5 E% f6 a- `
lamda =
. h# n. Z. A5 N d2 f- JColumns 1 through 2
5 S( h5 j' V* g" i! S0.000000000000000 + 3.020447918044219i 0.000000000000000 + 0.000000000000000i
* z4 h& Q4 L# C$ s1 I8 i0.000000000000000 + 0.000000000000000i 0.000000000000000 - 3.020447918044219i
0.000000000000000 + 0.000000000000000i 0.000000000000000 + 0.000000000000000i
$ {+ ^4 x9 I/ ~+ e8 b# V0.000000000000000 + 0.000000000000000i 0.000000000000000 + 0.000000000000000i
Columns 3 through 4
]; I) I9 O6 |7 x7 {0.000000000000000 + 0.000000000000000i 0.000000000000000 + 0.000000000000000i
0.000000000000000 + 0.000000000000000i 0.000000000000000 + 0.000000000000000i
-0.000000000000000 + 0.936426384924271i 0.000000000000000 + 0.000000000000000i
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？