= Description of curves for light purposes
Since the daily cycle is the main factor for plants whatever the periodicity of
the curve it will be restarted at midnight local time.

== Curve definition
To keep it simple, we will only consider linear change.
Because of this the light value can be described in required brightness at
a given time. The value that the light had before that will then be adjusted
smoothly, until it reaches the value intended at the next time point.
The brightness at midnight must always be declared.

For example: We want the light to be on off during the night, then turn on at
6:00 in the morning with 20% and gradually increase in brightness until it
reaches 100% at 8:00. Then, at 21:00 we want the light to start dimming until
it turns off at 23:00. The following graph shows this:

.Graph not yet available
[%collapsible]
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The points should then be defined as follows:
[source]
----
0000 0.0
0600 0.0
0600 0.2
0800 1.0
2100 1.0
2300 0.0
----

You will notice that two entries are at the same time here. This will make sure
that the light stays at the same level during the duration from 0000 to 0600.
When multiple entries are at the same time, the furthest down will be chosen.

