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NAME
       Smokeping::matchers::Medratio - detect changes in the latency median

OVERVIEW
       The Medratio matcher establishes a historic median latency over several
       measurement rounds. It compares this median, against a second median
       latency value again build over several rounds of measurement.

       By looking at the median value this matcher is largely immune against
       spikes and will only react to long term developments.

DESCRIPTION
       Call the matcher with the following sequence:

        type = matcher
        pattern =  Medratio(historic=>a,current=>b,comparator=>o,percentage=>p)

       historic
           The number of values to use for building the 'historic' median.

       current
           The number of values to use for building the 'current' median.

       comparator
           Which comparison operator should be used to compare current/historic
           with percentage.

       percentage
           Right hand side of the comparison.

         old <--- historic ---><--- current ---> now

EXAMPLE
       Take   the  12  last median values. Build the median out of the first 10
       and the median from the other 2 values. Divide the results and decide if
       it is bigger than 150 percent.

        Medratio(historic=>10,current=>2,comparator=>'>',percentage=>150);

        med(current)/med(historic) > 150/100

       This means the matcher will activate when the current latency median  is
       more  than  1.5  times  the historic latency median established over the
       last 10 rounds of measurement.

COPYRIGHT
       Copyright (c) 2006 by OETIKER+PARTNER AG. All rights reserved.

SPONSORSHIP
       The  development  of  this  matcher  has  been  paid  for   by   Virtela
       Communications, <http://www.virtela.net/>.

LICENSE
       This  program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as  published  by  the
       Free  Software  Foundation; either version 2 of the License, or (at your
       option) any later version.

       This program is distributed in the hope that  it  will  be  useful,  but
       WITHOUT   ANY   WARRANTY;   without   even   the   implied  warranty  of
       MERCHANTABILITY or FITNESS  FOR  A  PARTICULAR  PURPOSE.   See  the  GNU
       General Public License for more details.

       You  should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation,  Inc.,
       675 Mass Ave, Cambridge, MA 02139, USA.

AUTHOR
       Tobias Oetiker <tobi@oetiker.ch>

2.8.2                              2024-02-04..::lib::Smoke...hers::Medratio(3)

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