negative zero as eigenvalue
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Hello,
Why do I get negative zero as eigenvalue?
ans =
0.2615 0.1950 - 0.3938i
0.1950 + 0.3938i 0.7384
>> eig(ans)
ans =
-0.0000
1.0000
thanks
2 Kommentare
abhijit kulkarni
am 10 Apr. 2014
I think that negative zero implies that it is not treated as positive integer.
Refer: The IEEE 754 standard for floating-point arithmetic (presently used by most computers and programming languages that support floating point numbers) requires both +0 and −0. Real arithmetic with signed zeros can be considered as a variant of the extended real number line such that 1/−0 = −∞ and 1/+0 = +∞; division is only undefined for ±0/±0 and ±∞/±∞.
Negatively signed zero echoes the mathematical analysis concept of approaching 0 from below as a one-sided limit, which may be denoted by x → 0−, x → 0−, or x → ↑0. The notation "−0" may be used informally to denote a small negative number that has been rounded to zero. The concept of negative zero also has some theoretical applications in statistical mechanics and other disciplines.
It is claimed that the inclusion of signed zero in IEEE 754 makes it much easier to achieve numerical accuracy in some critical problems,[1]
Akzeptierte Antwort
Mischa Kim
am 10 Apr. 2014
Suma, it's not really zero. Set the display format to long fixed decimal:
format long
[v, d] = eig(a)
v =
0.381333979059441 - 0.770099081813373i 0.226935196532721 - 0.458292719972234i
-0.511401799571426 + 0.000000000000000i 0.859341724458383 + 0.000000000000000i
d =
-0.000011841043894 0
0 0.999911841043894
5 Kommentare
Mischa Kim
am 10 Apr. 2014
i is the imaginary unit. Since the matrix is complex you can expect the eigenvectors to be complex as well.
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