【正确答案】用下面的命令来求解该题。
   disp('Problem 8.8')
   EO=1.0;
   Im=[5.4016 4.6037 2.6930 2.6720 0.9445]:
    t=[0.0042 0.0208 0.3208 0.3375 10.004];
   I=Im/sqrt(2);
   id=I(5);
   Dt2=[t(3)  t(4)];
   Di2=I(3)-idI(4)-id];
   LDi2=log(Di2);
   c2=polyfit(Dt2,LDi2, 1);
   iddash=(exp(c2(2))+id)
   Xddash=E0/iddash
   taudash=abs(1/c2(1))
   Di=(iddash--id)*Eexp(-t(1)/taudash)exp(-t(B)/taudash)];
   Di1=[I(1)Di(1)-id I(2)-Di(2)id];
   LDil=log(Dil):
   Dt1=[t(1)t(2)];
   c1=polyfit(Dt1,LDi1,1);
   id2dash=exp(c1(2))+iddash
   Xd2dash=E0/id2dash
   tau2dash=abs(1/c1(1))
   t=0:.005:.045;
   fit2=polyval(c2,t);
   fit1=polyvaI(c1,t);
   plot(t,fitl,t, fit2),grid
   ylabel(Ln(I),pu')
   xlabel('t,sec')
   结果为：
   I'_d=2.2273p.u. X'_d=0.4490p.u.   τ'_d=1.3821s
   I"_d=4.0024p.u. X"_d=0.2498p.u.    τ"_d=0.0397s