function f=tf2sym(g)
%This function transform tranfer function to sym form function.
%g(s)-->f(x)
%-------------------------------------------------------|%
%|(C)2005 Bui Trung Hieu				|%
%|Website: www.khvt.com					|%
%|Email: matlab@khvt.com				|%
%-------------------------------------------------------|%

exponent=g.iodelay;
[z,p,fac]=zpkdata(g,'v');
f=sym('1');
syms x
k=1;
while(k<=length(z))
    f=f*(x-z(k));
    k=k+1;
end
k=1;
while(k<=length(p))
    f=f/(x-p(k));
    k=k+1;
end
f=f*fac*exp(-exponent*x);
%%End function