proc iml;
x1={0.92,2.10};
x2={-0.38,8.85};
s1={40.8973 6.3644,6.3644 59.6867};
s2={6.2084 -0.3378,-0.3378 18.5450};
x=(x1+x2)/2;
s=(s1+s2)/2;
a=inv(s)*(x1-x2);
x0={0.6,3.0};
w=t(a)*(x0-x);
print w;