% Scalar ARE

a = 1/2;
b = 1;

q = 0;
r = 1;

s2 = (b^2*a^2-b^2)
s1 = (b^2*q - r + r*a^2 - a^2*b^2)
s0 = r*q

s = roots([s2 s1 s0])