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;%
8 X  m+ @, ?9 ]/ Cc1=0;c2=0;
x0=[1;0];xd0=[0;0];tf=50;dt=0.1;
% W; P! S: S$ L9 Y8 wM=[m1,0;0,m2];k=[k1+k2,-k2;-k2,k2];
c=[c1+c2,-c2;-c2,c2];
  _  s8 U5 j0 F1 V/ Y8 o: Y) ]! SA=[zeros(2,2),eye(2);-M\k,-M\c];
- j. n, w8 O# ?" v/ Z0 my0=[x0;xd0];
for i=1:round(tf/dt)+1
. D& o) k: A1 \0 x/ F# e    t(i)=dt*(i-1)
    y(:,i)=expm(A*t(i))*y0;
% p" w; ]2 q5 z+ g) y6 kend
subplot(2,1,1),plot(t,y(1,),grid  
- h& n' X; ?6 r1 ysubplot(2,1,2),plot(t,y(2,),grid
& P& ?/ {+ ?2 V4 O[p,lamda]=eig(A)



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. x& D% ^& ~) |. y, R6 S: llamda =
2 B0 M8 w; F+ w; U( b; n- o0 e  Columns 1 through 2
  0.000000000000000 + 3.020447918044219i  0.000000000000000 + 0.000000000000000i
+ _. @& `" {+ C# L+ ?- y+ |2 j  0.000000000000000 + 0.000000000000000i  0.000000000000000 - 3.020447918044219i
) M( y& _% Z4 L  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
% z2 v7 n! |3 E  W/ E+ Y8 E1 [7 y  Columns 3 through 4
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
  0.000000000000000 + 0.000000000000000i  0.000000000000000 + 0.000000000000000i
-0.000000000000000 + 0.936426384924271i  0.000000000000000 + 0.000000000000000i
9 O2 c- U  S7 ?  0.000000000000000 + 0.000000000000000i -0.000000000000000 - 0.936426384924271i
" s& S4 A2 s! ~% W$ w

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; j: L' X/ H$ r2 \$ g7 U" B
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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？