無阻尼二自由系統固有頻率的程序

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% 無阻尼二自由系統固有頻率的程序 20180401A
+ v2 z8 l3 F: B/ Q) r# e1 ym1=100;m2=100;k1=200;k2=400;%
c1=0;c2=0;
: {+ [% Z& X' f2 K( @x0=[1;0];xd0=[0;0];tf=50;dt=0.1;
M=[m1,0;0,m2];k=[k1+k2,-k2;-k2,k2];
9 `% N; v. }9 jc=[c1+c2,-c2;-c2,c2];
. [3 X" ^6 T' [0 p# KA=[zeros(2,2),eye(2);-M\k,-M\c];
9 t% v* R: B7 ]+ h  j( G' Oy0=[x0;xd0];
for i=1:round(tf/dt)+1
    t(i)=dt*(i-1)
    y(:,i)=expm(A*t(i))*y0;
end
subplot(2,1,1),plot(t,y(1,),grid  
subplot(2,1,2),plot(t,y(2,),grid
+ \3 A. |( N5 e- G! l[p,lamda]=eig(A)

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lamda =
  Columns 1 through 2
1 f  j6 t; i7 [5 j  0.000000000000000 + 3.020447918044219i  0.000000000000000 + 0.000000000000000i
$ v2 e) ~5 X2 S* R( o  0.000000000000000 + 0.000000000000000i  0.000000000000000 - 3.020447918044219i
- a/ z: O- p! i6 y# ]: r7 r$ v6 E# |  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
+ ]/ `1 ^/ b6 o( }% G% D! L  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
/ J" _3 l6 l& ^1 T( O  Columns 3 through 4
' q. z1 l9 D1 \0 Y- ]5 n' p" r  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
4 n1 ?9 b4 G. Q1 c" l- ~7 w' \+ H  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
3 z3 U: r4 F& z# P, c! N+ g! C) z( Y -0.000000000000000 + 0.936426384924271i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i -0.000000000000000 - 0.936426384924271i

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鴻鵠重工

代碼中有個笑臉是啥意思，此處應該是什么代碼？