[rrd-developers] logarithmic functions
temporary.212 at kidmillennium.net
Sun Nov 23 00:39:09 MET 2003
The current logarithmic functions in rrdtool are limited to natural
logs, which necessarily means no logs of base <1.
I plan to implement a system allowing different logarithmic bases and
hopefully adjust the autoscaler to make bring out the important parts
(including manipulating the log base).
Logarithmic plotting helps when you have exponential data, but it also
helps when you have data with generally little change spiked by huge
changes, and you don't want to cut the data from the huge changes.
If anyone is or has worked on similar ideas, please let me know what's
I'm considering the best most intuitive ways to take information and
which variables should be allowed:
-logarithmic base (e, 10, 8, 2, 0.1, etc)
-upper-exponent (not sure about this as it is syn with --upper-limit)
-lower-exponent (-10, 0, 15--also syn with -lower-limit)
I'm looking at trying to make an exponent autoscaler that would
attempt to bring out the meaningful data. It will find an appropriate
base. As the base gets closer to one, the scale gets closer to
linear. From 1 down to 0 it gets exponential in the opposite
direction (i.e. instead of stretching data on the top of the graph, it
will stretch the bottom).
Another idea might be to use a varying function for the base that
would stretch the top and the bottom or compress both.
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