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

**From**: |
Ben Abbott |

**Subject**: |
Re: what does 'mpoles' function do ? (what is 'poles' in it ?) |

**Date**: |
Sat, 25 Jun 2011 18:55:13 -0400 |

On Jun 25, 2011, at 5:13 PM, Sergei Steshenko wrote:
>* 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.*
You're inference is correct.
mpoles() is used by the residue() function to identify a multiplicity of poles
for A(z)/B(z).
Ben