%The Routh-Hurwitz stability criterion is a necessary (and frequently
%sufficient) method to establish the stability of a single-input,
%single-output (SISO), linear time invariant (LTI) control system.
%More generally, given a polynomial, some calculations using only the
%coefficients of that polynomial can lead us to the conclusion that it
%is not stable.
%in this program you must give your system coefficents and the
%Routh-Hurwitz table would be shown
%
% Farzad Sagharchi ,Iran
% 2007/11/12
clc
clear
r=input('input vector of your system coefficents: ');
m=length(r);
n=round(m/2);
q=1;
k=0;
for p = 1:length(r)
if rem(p,2)==0
c_even(k)=r(p);
else
c_odd(q)=r(p);
k=k+1;
q=q+1;
end
end
a=zeros(m,n);
if m/2 ~= round(m/2)
c_even(n)=0;
end
a(1,:)=c_odd;
a(2,:)=c_even;
if a(2,1)==0
a(2,1)=0.01;
end
for i=3:m
for j=1:n-1
x=a(i-1,1);
if x==0
x=0.01;
end
a(i,j)=((a(i-1,1)*a(i-2,j+1))-(a(i-2,1)*a(i-1,j+1)))/x;
end
if a(i,:)==0
order=(m-i+1);
c=0;
d=1;
for j=1:n-1
a(i,j)=(order-c)*(a(i-1,d));
d=d+1;
c=c+2;
end
end
if a(i,1)==0
a(i,1)=0.01;
end
end
Right_poles=0;
for i=1:m-1
if sign(a(i,1))*sign(a(i+1,1))==-1
Right_poles=Right_poles+1;
end
end
fprintf('\n Routh-Hurwitz Table:\n')
a
fprintf('\n Number Of Right Poles =%2.0f\n',Right_poles)
reply = input('Do You Need Roots of System? Y/N ', 's');
if reply=='y'||reply=='Y'
ROOTS=roots(r);
fprintf('\n Given Polynomials Coefficents Roots :\n')
ROOTS
else
end
