# Octave 4.0.3, Fri Nov 03 10:52:13 2017 GMT <unknown@STR40101-AULA1>
A = [11 -1 -4; -1 11 -4; -4 -4 14]
A - A'
[B,Lambda] = eig(A)
1/sqrt(3)
det(B)
B(:,3) = -B(:,3)
det(B)
cosalpha = (trace(B) - 1)/2
alphar = acos(cosalpha)
alphagradi = alphar * 180/pi
[autovettori, LambdaB] = eig(B)
B * B'
autovettori * autovettori'
1/10
format long
1/10
a = 1/10
for k = 1:20 a=11*a-1 end;
quit;
# Octave 4.0.3, Fri Dec 22 09:50:19 2017 GMT <unknown@STR40101-AULA1>