[rrd-users] Re: rate of change

Aaron Spiegel spiegela at birch.net
Tue Nov 4 17:37:12 MET 2003


Its only more accurate if you fetch out more than two datapoints, tho :)

On Nov 3, 2003, at 10:40 PM, Aaron Spiegel wrote:

> For more accurate "rate of change" you can fetch the data out of the
> rrd (into perl for example), and use the perl Math::Interpolate module
> to get a best fit function from the points with time being the x values
> and y being the disk space usage, and then use Math::Derivative to get
> the second derivative of that function.  The second derivative of a
> function is by definition the rate of change.

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