為什么這個程序在matlab7.1中運行不了

maxluck110

t=0:0.1:12:num=[1];
4 C3 H; Y4 H1 c6 z1 _Zeta1=0:den1=[1 2*Zeta1 1];
2 Q: Z" `" u* M6 d" [Zeta2=0.3:den2=[1 2*Zeta2 1];
! Z7 g* y" E! {- Y9 L/ dZeta3=0.5:den3=[1 2*Zeta3 1];
Zeta4=0.7:den4=[1 2*Zeta4 1];
Zeta5=1:den5=[1 2*Zeta5 1];
! N/ k" v4 p2 l5 ?0 j[y1,x,t]=step(num,den1,t);
- C' S( p$ C0 _( {[y2,x,t]=step(num,den2,t);
[y3,x,t]=step(num,den3,t);
, C+ E9 `& h4 W& t4 L" I[y4,x,t]=step(num,den4,t);
[y5,x,t]=step(num,den5,t);
5 O( l/ G$ i. k' |8 tplot(t,y1,t,y2,t,y3,t,y4,t,y5);
! X! x) @8 H+ }% b% Fgrid on;