what is the meaning of (left half plane of roots)?

the roots

b=

-0.3642 + 0.7125i

-0.3642 - 0.7125i

0.3642 + 0.7125i

0.3642 - 0.7125i

does it means only the real roots only?

or

the first two rows?

Answer 1

[Voss]

The left half-plane refers to the part of the complex plane where the real part is less than 0 (or <= 0 if you want to include the imaginary axis).

b=[
  -0.3642 + 0.7125*i
  -0.3642 - 0.7125*i
   0.3642 + 0.7125*i
   0.3642 - 0.7125*i]

b = 
  -0.3642 + 0.7125i
  -0.3642 - 0.7125i
   0.3642 + 0.7125i
   0.3642 - 0.7125i

b(real(b) < 0)

ans = 
  -0.3642 + 0.7125i
  -0.3642 - 0.7125i

In this case, the first two elements of b (which is the first two rows) are in the left half-plane, yes.

[ali temsah]

thanks alot .

that was confusing

[Voss]

You're welcome!