# Description of the program: extrema

This program determines the maxima (minima) of a time series. This corresponds to a Poincaré section at the zeros of the derivative. To get a better estimate of the extremum, a quadratic interpolation is done.

Note: Very sensitive to noise!

## Usage:

extrema [Options]

Everything not being a valid option will be interpreted as a potential datafile name. Given no datafile at all, means read stdin. Also - means stdin

Possible options are:

Option | Description | Default
--- | --- | ---
-l# | number of points to use | whole file
-x# | number of lines to be ignored | 0
-c# | column to be read | 1
-z | determine minima instead of maxima | maxima
-t# | minimal time required between two extrema | 0.0
-o# | output file name | without file name: 'datafile'.ext (or stdin.ext if data were read from stdin) if no -o is given stdout is used
-V# | verbosity level 0: only panic messages 1: add input/output messages | 1
-h | show these options | none

## Description of the Output:

The output consists of two columns:

- The position of the extremum
- The time between the last two extrema

View the C-sources.

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