what does 'mpoles' function do ? (what is 'poles' in it ?)

[Sergei Steshenko]

Hello,

'mpoles' function (http://octave.sourceforge.net/octave/function/mpoles.html)
can be found under "Finding Roots" - see
http://octave.sourceforge.net/octave/overview.html .

So, because of the "Finding Roots" I _guess_ the function deals with _roots_.

However, the description talks about poles.

I studied math and calculus quite a time ago, so I could easily forget what
it's all about. AFAIR, if we have a

numerator / denominator

expression, and both numerator and denominator are polynomials, then
roots of numerator are called zeros and roots of denominator are called
poles. But both zeros and poles are related to the whole expression.

But other than that I do not know what poles have to do with polynomials.

Could anybody please clarify regarding 'mpoles' and poles it deals with ?

Thanks,
  Sergei.