function engzzy(zeta2)
n=length(zeta2);for k=1:n;Num{k,1}=1;Den{k,1}=[1 2*zeta2(k) 1];end
S=tf(Num,Den);				%
t=(0:0.4:30)';				%
[Y,x]=step(S,t);				%
tt=t*ones(size(zeta2));		%
ribbon(tt,Y,0.4)				%
%
view([150,50]),shading interp,colormap(jet)%
light,lighting phong,box on					%
for k=1:n;str_lgd{k,1}=num2str(zeta2(k));end,legend(str_lgd)%
str1='\itG = (s^{2} + 2\zetas + 1)^{-1}';
str2='\fontsize{16}\fontname{隸書}取不同';
str3='{\fontsize{10}\it\zeta}';
str4='\fontsize{16}\fontname{隸書}時的階躍響應';
title([str1,str2,str3,str4]),zlabel('\ity(\zeta,t) \rightarrow')