damping factor - xi or zeta?

[electricpete]

I know it's a stupid question but I'd like to know so I can be consistent with the rest of the world.

In all of my textbooks the 2nd order system is described as
H(s) = w0^2 / (s^2 + 2*squiggle*w0*s + w0^2).

What is the correct greek letter for that squiggle. (I looked up the symbols and eta and xi both look pretty similar to me).

Thanks.

 

[electricpete]

small zeta looks like this &[ignore]zeta[/ignore];
small xi looks like this &[ignore]xi[/ignore];

 

[GregLocock]

small zeta according to two references Cheers

Greg Locock

 

[MikeyP]

I would always use zeta. In my handwriting both just look like a random squiggle.

M

 

[electricpete]

Thanks guys.